Unlike trying to analyze why Josh is a pedophile or zoosadist, his mental health is straightforward. Josh is first and foremost a narcissist. His entire personality is based on a grandiose image of himself (perhaps based on him being good at IT class in public school), where he is an important person at the center of the world who deserves the highest status. He is specifically of the covert narcissist subtype, which causes his frequent narc rages because he inherently knows deep down that he is nothing special and every single slight and criticism against him digs up his deep seated inferiority complex. Antisocial personality disorder is likely as well.
The reason Josh feuded so hard with Nick Rekieta (to the point of multiple times arguing with him after publically saying he would no longer speak to him) is because the two are essentially the same person being mentally ill narcissists who suffer from ODD, but Rekieta had (and still mostly has) everything Josh always wished he could have. A trust fund, a house in a White community, parents who love him, a White wife and kids, being thin, and being an eceleb people regularly tuned in to listen to. The only actual difference is Josh's version of going to Hedonism 2 would be him going to Indonesia to watch monkey torture videos being filmed in between raping kids. I do NOT want to analyze why Josh is so psychosexually depraved, all I can guess is that he represses because whatever the reason, even Josh knows he is a disgusting pervert.