Except that he made way more money than any MMA fighter, is a household name in Europe, fills the stadiums and is watched by many more people live than anyone in the UFC could ever dream of. HW boxing division has a deeper talent pool than any division in MMA where most fighters come from either USA or Brazil. Boxing is global and if boxing HW division would be so easy then those MMA fighters would have gone there instead and earn millions like Wilder, Joshua, Fury, Povetkin... All of them making more money than anyone in the UFC