Ever wonder how frequently people call them out? After a while it just gets irritating, so they just perma ban instantly to get the point across. It has nothing to do with popularity "going to their heads" as much as just popularity in general. When you get to be popular on the internet, you accrue much more hate, and its less stressful to just filter it out than it is to watch it pile up. Just look at pewdiepie, (p.s. I don't like him either) he completely disabled YouTube comments. Why? not because he's cocky, but because the comment section was dominated by asshats and other forms of douchebaggery.