If he does decide to leave, then he certainly shouldn't go over to Boxing.
With that fanbase the average IQ level is around 40-50 at BEST. Trying to have a worthwhile discussion online about it is surprisingly met by hostile early to mid teens, and also old men with the mental capacity of early to mid teens(in other words this particular fanbase never grows up).
They are only fans of 1 or 2 fighters instead of the whole sport, and it's an unhealthy obsession instead of a fandom. Any other fighter who is even a hint of a rival to this favorite fighter sucks, is overrated, everybody around them is a bum etc. If their favorite loses then he too, was never any good. 1 loss? Forget about it, should retire, his career is completely over, he should jump off a bridge etc.
MMA is only a light version of the atrocity I just described above. Kickboxing/Muay Thai communities and perhaps Grappling are not as bad, there is still a sense of martial arts respect there. But who's got time for those niche sports? I love watching them from time to time but they're not A-level combat sports and an Anik isn't gonna go over there.