How can a fighter be 'broken' or 'shot' after one defeat/KO?

Bute had his **** together in the 12th, he may just have gotten his edge back

 

Davey Moore

 

I'm just speculating here, but there seems to be some fighters (such as Hamed) with a brittle confidence based on success, a certainty in their invincibility which can lead to them taking the kind of risks which may lead to them winning fights and thus feeding off itself. When this bubble is finally burst though, the realisation that they are fallible, and always were, can lead to a devastating loss of confidence in the ring. I suspect this kind of mindset is probably exacerbated by the propensity of successful, ego driven, fighters to attract sycophantic entourages, and hangers on who will tend to stoke the fighters' ego still further. The tendency of fans and the media to talk about fighters as being unbeatable probably doesn't help either.

I guess I'm talking about believing your own hype.

Of course the mentally tougher fighters, specially those who have perhaps suffered losses earlier in their career, but continued to fight anyway, are less likely to suffer so dramatically from the loss of a single fight.