COSTNER RISKS EVERYTHING ON BIG MOVIE BET!

Friends worry he'll wind up a broken man

FRESH off his dirty divorce, cowboy king Kevin Costner is getting makeovers and working to the bone — writing, producing, directing and starring in an epic movie Western — leaving pals fearing it’s too much and he’ll suffer a devastating, delayed meltdown.

Costner’s career gamble, the two-part flick Horizon: An American Saga, is due out next summer and his ego and money are riding on it, snitch sources.

“Kevin is heavily, personally invested and not just his time and effort,” spills an insider. “He has a ton of his Yellowstone money in this thing, and knows there’s no guarantee of success.”