The YouTube star was due to fight at Madison Square Garden this weekend.
But Paul decided to pull the plug on the whole thing after Rahman Jr apparently tried to move the goalposts.
A statement from Most Valuable Promotions said Rahman’s team tried to change the agreed upon weight limit from 200lbs to 215lbs.
And KSI said on his YouTube channel: “I think there’s a couple of reasons why Jake Paul versus Hasim Rahman didn’t happen.
“First of all – I think Dana White mentioned something like this – they weren’t selling. There were still lots of tickets to be sold. It costs a lot to put the lights on at MSG.
“I just don’t think Jake Paul could afford to fight at MSG. He doesn’t have the clout, fam. He doesn’t have the sauce like that, especially to fight a nobody.
“For me, I can fight a nobody like Alex and sell out, it’s as simple as that.
“Bro, Jake Paul’s out here charging sixty dollars. More than Usyk versus AJ. Do you know what you could do with sixty dollars?
“With sixty dollars, you could go to a nice restaurant, go to the O2 to watch me annihilate Alex Wassabi. You could even buy my pay-per-view and still have money left over to buy snacks and drinks and whatever the f**k you want. You could literally buy Prime, buy Sides, and watch the pay-per-view, all in the comfort of your own home.
“Like it was crazy, Jake Paul was literally robbing his audience, and some of his audience would actually pay for it – that’s the sad thing. Some poor souls spending money getting scammed by this guy, fam.
“I can understand if it was a big fight. You versus Tommy Fury, fine, sixty dollars, a lot of people are going to want to see that. But you versus Hasim? Nah.
“Also, to give Jake the benefit of the doubt, I think Hasim was trying to play a fast one. I think Hasim didn’t give a f**k about the money, he just wanted to be that guy who knocked out Jake Paul, and he wanted every advantage that he could get.
“Fair enough, you know, he tried it. At the end of the day they both lost out as they’re just sitting at home with their d**ks in their hands making no money.”
WATCH: KSI’s brutal reaction to the news that Jake Paul’s fight with Hasim Rahman Jr has been cancelled
Check out the video below…