In the late ’80s, Kevin Costner made what seemed like a reckless career decision. He turned down the lead role of Jack Ryan in The Hunt for Red October—and “more money than I had ever seen,” as he put it to GQ—to direct and star in Dances With Wolves, an ambitious Western that most studios did not want to make. Though it was Costner’s directorial debut, it proved to be a staggering success. It earned 12 Oscar nominations and seven wins, including both best picture and best director for Costner, who beat out Francis Ford Coppola and Martin Scorsese. Costner, who put in $3 million of his own money to finish the film, was expected to take home a $50 million back-end payout and earned a ranking alongside Tom Cruise as one of the most powerful men in Hollywood.

Now, at 69, Costner has taken a familiar-sounding risk—though this time he has raised the ante significantly. He walked away from his $1 million-per-episode gig on Yellowstone, the popular Paramount series that reignited his career, and claims he is scheduled to put more than $100 million of his own money into a four-movie Western franchise that no studio wanted to bankroll, even as a stand-alone. And he’s done it at retirement age.

“I’ve mortgaged 10 acres on the water in Santa Barbara where I was going to build my last house,” Costner told Deadline last month, speaking about his quest to make Horizon: An American Saga. “It has thrown my accountant into a fucking conniption fit. But it’s my life, and I believe in the idea and the story.”

Costner has had some version of Horizon in mind since 1988, before Dances With Wolves was released. When he commissioned the story, it was as a single conventional Western. But Costner’s vision ballooned into a four-installment franchise with the help of screenwriter Jon Baird. “Kevin, let me get this straight. Nobody wanted to make one, right?… Why do you then go out and write four more?” Costner cracked to GQ. “I can’t defend that psyche.” He later told New Yorker editor David Remnick, “I scratch my head a little bit at my own behavior…. I didn’t know it was going to translate into as much money.”

But the filmmaker does not like to compromise creatively. So when studios complained that the scripts were too long (the first film clocks in at three hours), the subtitles would be too problematic, and the production (which required period costumes, horses, and expensive Utah location shoots) would be too expensive, he wouldn’t budge. Not for his vision, not out of concern for how this gamble would make him seem to the world, and not out of fear of losing the fortune he’d built. “Ultimately, I just looked at the pile that I had, and I thought, Well, I’m not going to let that control me,” he told Remnick. “And so I decided to put that at risk in order to make this.”

Costner cast himself, Sienna Miller, Sam Worthington, and Jena Malone in the franchise, a sprawling ensemble with Civil War–era storylines. When Miller received the scripts, she recalled, the actor was “very confused” by their length—initially thinking he was sending her a TV show. “It’s unheard of to set out to make four films unless it’s Lord of the Rings or Harry Potter,” she told VF. When Vanity Fair put Costner on its cover in 1992—in the wake of Dances With Wolves’ success—Jim Wilson, the filmmaker’s then producing partner, explained, “Kevin doesn’t live by the rules. If there’s a rule to be broken, he likes to take that tack.”

Perhaps unsurprisingly, then, much about the films’ rollout is unprecedented. Warner Bros. is distributing and helping to market the films, with Costner bankrolling the actual advertising. (According to The New York Times, “the deal’s structure means that should the movies backfire, there will be little financial downside for the studio but much risk for Costner himself.”) The first two Horizon films, which reportedly cost around $100 million each, will both premiere this summer—Chapter 1 opens Friday, while Chapter 2 bows on August 16.

Costner finally unveiled Horizon: An American Saga—Chapter 1 to the world at last month’s Cannes Film Festival, where he got an 11-minute standing ovation. But afterward, critical reviews proved more mixed. “A jumble of clichéd plots rendered in washed-out color (and washed-out performances), Horizon may rival Megalopolis as the biggest American boondoggle at this year’s Cannes,” wrote VF’s Richard Lawson. “Sure, what appears disorderly may turn out to be genius by the time we’ve seen the end of the project—but 10 hours is an awfully long time to wait to find out.”

Early tracking suggests that Horizon will open to a lackluster $10 million to $12 million. And Costner has much at stake: “I put in all this cash, and I basically deferred my writing, my producer, directorial, and my acting fees,” the filmmaker told Deadline. “So I have an enormous amount in this…. It’s not the smartest move, but…I’m not the greatest businessman.”

This isn’t his first bet since Dances With Wolves. Costner also put some of his own money into 1997’s The Postman, his second directorial effort—a postapocalyptic adventure film that earned about a quarter of its budget at the box office and a handful of Razzies, including for worst picture. When he directed again, returning to the Western genre in 2003’s Open Range, Costner did it, he says, without taking a salary. (That gamble fared better, with the film earning positive reviews and a gross of nearly $70 million against a reported $22 million budget.) He also put in a reported $9 million to make the 2015 release Black or White, a modestly reviewed drama written and directed by Mike Binder and costarring Costner and Octavia Spencer.

The Oscar winner has done an exhaustive press circuit for Horizon, appearing on the covers of everything from People and GQ to Cowboys & Indians, and dropping starry anecdotes to help bait audiences along the way. He told Howard Stern about working with the late Princess Diana to plot out a Bodyguard sequel in which they would both star. (“She said, ‘Is there going to be a kissing scene?’ And I said, ‘Do you want there to be one?’ And she said, ‘Yeah,’ and I said, ‘Then we’ll do that.’”) He addressed rumors of a romance with Jewel, after photographs surfaced of the unexpected pair together on Richard Branson’s island. (“I don’t want these rumors to ruin our friendship because that’s what we have,” he told Stern. “She’s special to me. She’s beautiful enough to go out with.”) He reminisced about meeting a then unknown Ben Affleck and Matt Damon during an appearance on Jimmy Kimmel Live! last month. He even answered questions about The Bachelor. (“It’s really handsome people, beautiful women, and everybody’s trying to create a relationship in front of a billion people,” he told ET. “I have a little experience with that.”)

Mostly, though, he has had to answer many iterations of the question “why?” Why would Costner make this leap of faith, knowing the longevity of the commitment, the stress and complications it would involve, and the possible financial loss? Perhaps one of the few people on the planet who could possibly understand is Francis Ford Coppola, who, like Costner, unveiled his own expensive passion project at Cannes this year: Megalopolis.

“When you do go into the great unknown, you don’t want to say, ‘Oh, I wish I had done this or that.’ You want to say, ‘I got to do it,’” the filmmaker told Deadline during a moderated conversation with Costner. The Horizon filmmaker agreed: “That’s how I feel about it.”

But unlike Coppola, Costner is not close to being done with his gamble. He still has to find the financing to complete the franchise. And regardless of what happens when Chapter 1 bows at the box office, Costner has vowed to complete the series. “I know by hook or by crook, I’m going to make three,” he told IndieWire. “And by hook or by crook, I’m going to make four.”

Though he’s made it seem as though he will make these films by any means necessary, a dud weekend will make it even more difficult for him to find additional financing for a franchise already undesired by studios. While Costner told VF that he was already working on the third Horizon film—fighting for more days of shooting—Horizon costar Sienna Miller told VF that filming for the third installment, which she said would supposedly be happening between August and November, had not yet been confirmed.

This weekend’s Horizon premiere will prove something else: whether Costner’s off-screen life is more interesting to audiences than the story he’s labored to put onscreen. The making of the film coincided with the messy dissolution of his second marriage, to Christine Baumgartner, with whom he shares three children. The divorce made headlines last year when Baumgartner requested more than $150,000 per month in child support, and the timing means that Costner has had to answer questions about surviving this personal chapter while promoting Horizon. “That’s a crushing moment,” the filmmaker told Gayle King this week in reference to his divorce, which was finalized in February. “It’s powerful. It hurt. But I go forward.” When asked point-blank by GQ whether the divorce was precipitated by Horizon, or the circumstances around its making, Costner said, “No, they’re not related.”

That being said, the filmmaker made clear that nothing in his life will stop him from finishing his Horizon quest: “I do have a level of responsibility to those guys that invested with me, to the people that believe in me, to the people that want to work all four of these,” he said in the same interview. “So it doesn’t matter how much water’s hitting me in the face, I can’t let go of the rope that is this thing.”

At the end of his conversation with The New Yorker—in which Costner again found himself confronted with the question of why—the filmmaker finally broke from all the stoic Western-moviemaking-speak.

“Honestly, after [making Horizon: An American Saga—Chapter] 4, I do need to rethink my life,” Costner said. “I need to think that I don’t need to put it all in the middle [of the poker table] again. I need to understand that I’m not going to define myself by the movies, and by the ones I’m doing and not doing. I need to figure out how to have more fun.”