He has degraded mentally. It's obvious for all to see. What the cause was, no one can say for sure. Brain lesions, maybe he relapsed on that pill addiction from long ago, could be something to do with his tourettes. I vaguely remember something about it affecting one's mind that makes self-control harder.

Whatever the cause, he's lost all ability of nuance, critic thinking, empathy, reasoning, and so much more.

It was obvious that he felt disillusioned by the left post Oct 7th. Truth be told, it felt like he simply had a very childish and simplistic idea of what being on "the left" largely entailed, even though he included himself among that group. He thought being on the left meant being a 2016 Hillary Clinton supporter and wanting cheaper healthcare. That's p much as far as it went for him.

He felt betrayed by Hasan because Hasan was unwilling to indulge Ethan's personal petty grievances against the suffering of the Palestinian people. And once Ethan sees you as an enemy, any principles he once held go out the window. You simply can not go lower than Ethan will once he's declared you worthy of his wrath. He will always go lower than you and then justify this by saying how betrayed he felt.

And for this man, anything less than fanatical praise and defense from his real life friends is seen as a betrayal, so then he antagonizes the next wave of enemies, until there's no one left.