Why do people hate Selena Gomez so much?

I get that her dating and being Justin biebers girlfriend can make someone(cue crazed fan girl)mad,espicially if you didnt like her in the first place but I mean come on death threats?she's getting death greats because of one guy out of millions that she decided to date?and Justin doesn't even know any of those mad fans,now don't get me wring I am a fan of Justin but I'm happy for them.their so cute together it makes me smile all cheesy like.anyway,to resume my question why do people hate Selena Gomez?she's a great singer in my opinion and a good actor,in fact I love almost all the the songs in her latest album(bang,bang,bang,who says,my dilemma,middle of nowhere,love you like a love song)and I don't know why's she's hated so much!