UFC's Justin Jaynes Has No Regrets For Betting, Losing $25K Fight Purse, Wants Rematch

UFC fighter Justin Jaynes bet his entire $25K fight purse on himself and LOST ... so, instant regret, right??

Nope ... 31-year-old JJ tells TMZ Sports he'd do it all over again -- and that's exactly what he wants to do.

"I really don’t have any regrets man. I live a high risk, high reward kind of lifestyle."

Of course, Justin famously gambled his fight check ... and ended up losing a 3-round split decision to 34-year-old Charles Rosa at UFC Vegas 30.

And now, he wants that cash back -- and he's willing to fight Rosa again.

"F*** it, let’s run it back, double or nothing," Jaynes says.

"I need to get my money back anyways man. It’s just one of those things, like I said I trained very, very, very hard. It was my motivation, there was a lot on the line going into this fight."

Even with the hit to his bank account (which sucked) ... Justin says he can still support his family -- and that's what really matters.

"It didn’t feel great, but it’s not going to put me in a position to where I can’t take care of myself," Jaynes says.