Stipe has been a UFC heavyweight since 2011 and has more title defenses than any other heavyweight. Heavyweights tend to get paid more and Stipe gambled on himself and won. Weidman did the same thing where he went into the Anderson fight making peanuts and then renegotiated his contract after that and made something like $500k to show in the rematch and in the rest of his title defenses. Overeem has also always made a lot for a non champion because heavyweight, they had to compete with outside organizations to sign him, and it's worth it to pay him rather than let him be a draw for Bellator, ONE, or K-1. Hell, as someone else already pointed out, the Reem cucked Stipe in his hometown by getting $800k to show, while Stipe got $600k.