The fighter who lost his belt and is being blasted as a phony by certain people don't want to be friends with the fighter who just almost killed him, losers don't want to shake hands and have a beer, they want to bash their opponents heads in still and want 12 more rounds just to get a chance to knock their opponents out, who they just lost to, Wilder has been carrying that grudge hatred pain embarrassment of that previous loss their second fight for years, he comes back and gets beat again stopped and Fury tries to be best friends, Wilder isn't having that, he needs time to let that hatred go, before he's becoming best friends with Fury.
The winner always wants to shake hands have dinner because he's happy, the loser is feeling hatred aggression towards their opponents who beat their butts & took their belts.
It's strange after talking about each others mothers, children, wives, dogs, cats, fish and cars, just talking crazy trash, wanting to cave each others heads in then all if the sudden after almost killing each other, it's time to be best friends ? this takes time, they program themselves to literally hate each other even almost fighting when coming close, normal rational people can't understand this behavior they believe it's only a game a media show, but they have hatred ill intent towards each other and really want to hurt each other, that's why fighters can kill someone in the ring, then fight another opponent months later and try to hurt the new opponents worse this is the mentality of a fighter , normal people would stop fighting because of the emotional pain guilt of killing someone for money and fame but fighters are hurting someone with punches defenseless or choking their opponents out and hold on continually choking them then smile and talk trash boxing keep pounding opponents seriously hurt bleeding trying to seriously hurt their opponents, these people don't want to be friends they are wired differently from ordinary people that's why they are fighters.
So understand why Wilder doesn't want to be best friends with the guy he hates and just tried to beat his head in trying to seriously hurt Fury talking about his mother.