Conor McGregor stands to make somewhere in the neighborhood of $100 million for fighting Floyd Mayweather next month. After that massive payday, multiple times more than he could make in an MMA fight, many are asking why McGregor would ever come back to the UFC.

Ever since the fight with Mayweather was announced, though, McGregor’s team has been adamant that’s coming back to defend his UFC lightweight title and it could be in December. John Kavanagh, McGregor’s head coach, doubled down on that notion Monday on The MMA Hour with Ariel Helwani.

“I don’t see any reason why he would not,” Kavanagh said of McGregor returning to the UFC. “Certainly money would not be the reason why he would not do MMA again. He has said very clearly to me, ‘Get ready, we’re back in the cage in December.’ I hope someone out there has sparked the interest in him to make him excited about that.”

Mayweather vs. McGregor, which takes place Aug. 26 in Las Vegas, is being promoted as “The Money Fight.” It’s obvious why. The fight will be one of the biggest pay-per-view events in history and it could generate something like $500 million in revenue, maybe more. Mayweather is the biggest drawing boxer; McGregor is his counterpart in MMA.

But while the money is obviously a reason why this fight is happening, Kavanagh said it’s really about more than for McGregor.

“It’s not money that’s motivating him anymore,” Kavanagh said. “He could very easily make similar money from doing some movies or doing endorsements. It’s the challenge. That’s why he’s in the gym laughing every day. If he left the gym now and stopped fighting, what would he do with his free time? You can only sit in one car at a time, you can only have one meal at a time. Eventually you want to do something that’s enjoyable to you. And that would be Conor drifting back into the gym. It’s what’s enjoyable to him.”

If that’s the case, then why wouldn’t McGregor fight in MMA again? He’s been the only two-weight concurrent champion in UFC history, but there is still history to be made. Still things no one else has done. Maybe McGregor would chase Tyron Woodley’s welterweight title. That trilogy fight with Nate Diaz is also out there and McGregor vs. Diaz is already one of the great rivalries in UFC annals.

Kavanagh said the incredible odds McGregor is facing against Mayweather — a 49-0, legendary boxer — is what's getting him into gloves every day. Not necessarily the windfall at the end of it.

“The motivation for this fight was not money, though of course it’s nice to be well paid for what you do,” Kavanagh said. “It was the challenge. And to be told again it’s impossible to do what he’s saying clearly what he is about to do.”