Really? I had a quick look and his fight pay doesn't seem great, what sort of sponsorship money is he bringing in per fight?
I don't know actually, his base pay in Bellator ain't great, but, afaik they do bonuses as well. And since being signed with Bellator he is fighting 4 and mostly 5 times per year, all with good sponsorship money I'm sure.
In the UFC he probably wouldn't have fought that often, Mitrione just complained about that for example. And he certainly is much freer to dictate his own career-path. He wants to fight in 3 weightclasses now. You think Dana would let him if he were a legit contender? (Even though I think its a mistake for him)
His Rizin tournament win earned him 300k, and I'm sure good opportunities in Japan sponsor-wise as well.
He is a well-established name in the scene and a character.
In the UFC he would fight less and lose more often imho. His stock would drop. And the Reebok deal would not be sweet for him either.