There isn't one singular event, but several of varying importance. Each one tipping him off more and more into his modern day insanity.
Anus whoring herself was just one of the reasons, but i believe that his catastrophic, disaster of an attempt at taking down Sam Hyde is where he digged his grave definitively. Everything that could've gone wrong went wrong and in the end he not only accidentaly resucitated Sam's career, but also killed his own.
He got outplayed and trolled, made himself look like a retard and essentialy gave Sam free publicity.
This is basically where the last of the old fans he had got off the bus, and where he had to permanently change his content for the worse in a desperate attempt to save his career by appealing to similar reddit cucks like him.
Mind you, he was already making cucked content before this, but it was only after Sam Hyde raped him online that Anus took the reins of his career as a whole, so nowadays anything he does has to include her in some way.