Tommy Fury says he is only fighting YouTuber Jake Paul to make money and that victory will give him “no credit in the boxing world”.
After a long-running online feud the pair will meet in Florida on 18 December.
Briton Fury, a professional boxer who appeared on Love Island, and American Paul have novice records, leading to the lucrative bout being criticised.
“The man’s not a fighter,” Fury said. “He’s a bum, he can’t fight.”
He told BBC Radio 5 Live: “I’m doing this for financial gain and making my name bigger in the US.
“You can’t talk about it in boxing terms. He doesn’t hold a title. He doesn’t hold any rankings. He’s not valued as a boxer, so there’s no other reason that I would be doing it.
“So thank you very much Jake Paul for letting me rob your bank account and not wear a mask and get away with it.”
Paul has a record of four wins as a professional, against fellow social media star AnEsonGib, ex-NBA basketballer Nate Robinson and mixed martial arts fighters Ben Askren and Tyron Woodley.
Fury, the half-brother of WBC world heavyweight champion Tyson, has seven professional victories, although his opponents have a combined record of 14 wins, 175 losses and two draws.
ALSO READ: FOOTBALL: City Beat PSG To Reach UCL Last 16
On Paul, whom he will fight at Amelie Arena in Tampa, 22-year-old Fury said: “Is he bringing new eyes to boxing? Yes. Is that good? Yes.
“But in terms of me fighting him, do I wanna knock him spark out? 100%. That’s all it’s about here.
“You can’t get away with fighting wrestlers, YouTubers, UFC fighters for very long.”
Before Love Island Fury had 12 amateur contests and trained under former world champion Ricky Hatton.
Fury said his “goal in life is to be world champion”.
“I’m not gonna win that by beating this idiot,” he said. “I’m beating this man, moving on to concentrate on my dreams.
“I’m gonna be straight back in the gym on the Monday after the fight because beating this man gives me no credit in the boxing world and credit in the boxing world is what I’m after.”