He's taken many too many blows to the head. Listen to interviews with him early in his career and compare them to his interviews now. The level of brain damage he's endured is pretty obvious.
Yeah I've got nothing but respect for his initial achievements and character. I'm not really an MMA follower but I saw some of his initial fights and interviews.
Not sure what happened since but it's clearly not good. I wonder if the kind of people you end up being around when you get that rich and famous are part of the problem. I'll never know so I can only speculate haha.
Honestly, he hasn't fought much in the last 8 years. His decline is 90% from alcohol and cocaine. His talent and work ethic was incredible during his rise, but after the Mayweather fight in 2017 he couldn't resist the Scarface lifestyle he had dreamed about. It's a sad story, not because he's a good person (he's not) but because he went from this athletic anomaly to a scared, weak, delusional has-been. Truly a literary tragedy.