Obviously I can't speak on who's fault it is, only a handfull of people probably really know the whole story. But I do think his management team were goofs for demanding the UFC co-promote with M1-Global or whatever it's called in order for Fedor to agree to fight in the UFC. I'm sure he could have made more money in the UFC than anywhere especially if the fight with him and Brock Lesnar would have been made.
And he would have retire with some dignity. Had Fedor joined with Nog and HH, and other HWs he would have racked up a few losses early on, but that's okay. He would have been pursuing the best. instead he chose to record protect, and take easy fights, many of which he ended up losing anyway. Perhaps the most humiliating was him taking on a natural MW in Henderson, and getting KO'd.
The UFC was brilliant in turning down Fedor and M1 demand to co-promote. He would have been expensive and would have given them no draw power whatsoever especially after he started falling to various HW's. Just look at how he drained every other promotion he went to. The guy never deserved the ranking he had for several years at the end of his career. He wasn't even top 5, but kept going up against washed out opponents that also were given inflated rankings. It was a big mess of nostalgic MMA fans and news organizations wanting to make him out to be something he was not.
Fedor went out trying to protect his record and failed. That's his legacy. Props to the UFC for rejecting him. And BTW, stop blaming M1 for what happened. Fedor was M1 and M1 was Fedor.