Well, I can imagine there being some bitchy behaviour and petty jealousies among opera singers at the top or among those who try to get there - it's (unfortunately) human nature.

Having said that, when I read posts at opera forums or comments at youtube I find many fans much worse - annoyingly so in fact. I've noticed it when it comes to discussions about instrumentalists also, but opera fans are the worst by far. They truly adore their faves (nothing wrong with that of course), but they also have a tendency to try to convince everyone else that compared to their personal fave(s) everyone else sucks. They only go watch a youtube from some singer to comment that it's no good and that their own God or Goddess does it so much better for example. The biggest prima donnas in opera are often not on stage but among the fans.