Jake Paul's leaving a ton of money on the table in his upcoming boxing match ... telling TMZ Sports he's more focused on being a world champion than selling Pay-per-views.

The 26-year-old Problem Child is facing off against 35-year-old pro boxer Andre August in Orlando next month ... which is a stark contrast from his usual big-name opponents like Tommy Fury, Nate Diaz and Anderson Silva.

Paul says that's by design ... as he needs to take on real-deal boxers to both silence his haters and move toward his goal of being the best fighter on the planet -- even if it doesn't line his pockets like his other high-profile bouts.

"This is probably just a break-even fight for me," Jake told Michael Babcock on the TMZ Sports TV show on FS1. "I probably won't even make money on it. Who knows what the outcome is. It's $200,000 for a private jet to fly around just to get me there and back."

But, that's not fazing Jake -- he makes it clear his only concern is polishing his skills and taking on a bigger challenge against a guy with more wins and knockouts under his belt.

"He's a beast, he's a dog and he's coming to win," Jake said of his opponent. "This is his make-or-break moment as a boxer himself. It's gonna be a really good fight."

Jake made a great point -- the entire world has watched all of his fights from the very beginning ... which is unprecedented for someone in the sport. Usually, dudes take on smaller bouts to gain more experience before getting big.

Jake explained he's not going to leave the massive PPV opportunities for good -- which might be good news for former boxing champion Andre Ward, who previously told us he was interested in taking on one of the Paul brothers in the future.

Jake said even though he could see himself taking on Fury, KSI or an MMA match with Nate Diaz down the road, his only goal right now is becoming the best possible pugilist he can be.