The former world champion is coming out of retirement for the eight-round fight at Hard Rock Stadium in Miami, which will have no judges and no official winner but a knockout is allowed.
Mayweather claims to have already made $30 million from the fight, with reports that figure could rise to €100m in total.
"I'm fighting a YouTuber who thinks he's a real fighter and I'm getting crazy money for it," Mayweather told reporters at Versace Mansion in Miami Beach.
"This is not a real fight for me. It's a real fight for him."
He added: "I retired from boxing but I didn't retire from entertainment and I didn't retire from making money," said Mayweather.
Mayweather, a former world champion across five division, retired with a perfect boxing record of 50-0, while Paul has fought once and lost, to fellow YouTuber KSI.
Even so, the 26-year-old believes he can hold his own against Mayweather, who is 18 years his senior and six inches shorter than Paul.
"There's a moment that goes through every fighter's mind, everyone we spar, everyone [Paul's brother] Jake's beaten, when we hit them and they realize 'Oh, he might not just do YouTube,'" said Paul.
"I think we're going to see Floyd's eyes light up the first time I hit him ... for Floyd's sake let's hope it doesn't get physical.