Eh, I think it's pretty obvious. Punk sold the image of him being "the different one" from every other wrestler you liked/was successful. He rode that image for almost 20 years. He admittedly is a shyt stirrer and likes to talk shyt. You combine that with that moral high ground stuff he loved the talk about and it should not be a that difficult to figure out why people go at him when he shows himself as just another wrestler who was carnying fans to make him money

a lot of fans take shyt personally, and specially the type of fan that Punk cultivated for almost two decades. It's obvious a number of them will act like scorned girlfriends when shyt doesn't go the way they envisioned.
And on the other hand, you have people like most of TSC were making fun of Punk is so easy these days that's it's impossible not to take some jokes in when the time arises