This sounds like the typical DF stuff that you find sometimes, regardless of the role. It's true, tho, that some tanks have some kind of god complex, but you can also find others that are nice and helpful. Just ignore the bad players (don't even bother to reply to their crap, don't give them the attention that they want), report them if they get too far, and be done with it. It's useless to think too much about it, and they don't deserve it either. Your gaming experience will be better on the long run, too.