There is definitely a stigma, but sometimes Bifags really ask for it on a personal level.>Talking about how annoying gays and trannies can act.>Bi person enters the conversation actually starts shit i didn't mention Bi people among "Annoying LGBT people" claiming erasure rather then getting that generally Bifags are chill.
And that's not getting into the good old "Posts straight content in porn dedicated forums and outlets", but ain't like faggots don't engage in that too and don't get similar hate when they post gay porn in straight dedicated stuff (unless it is lesbian Gay for obvious reasons).
I think it is less of a spectrum then assumed, people like to go "Sexuality is like a slider and no one is fully gay/straight" but people simplify shit only for their agenda, there ARE people on the extremes who genuinely are not only attracted by one gender by virtue of being disgusted by the genitalia of the other, or people who get off only because of a "thing", like say Dominating another man. and i don't think all these unique behaviors are all due one common cause or can all be "fixed" even if one can.
And since there are so many reasons to "be gay" there is obviously just as many reasons to find attraction to both genders.
And really, we all should know this by now, the "LGBT-Community" throws ALL letters under the bus when convenient and gives outrage, not just Bisexuals.
On a personal level it is probably just a inherent inferiority complex and jealousy of being able to go "normal", i noticed that in general it is hard for people to be understanding of sexual fetishes they don't share, which is why Gays and Lesbos get prejudiced against Straight and Bi people, only they lack the power to influence it due being a minority.
If a Bisexual or Straight person enters a LG dominated space the tables turn and you quickly see similar behaviour.
Also, Korra probably wanna fuck more then just Men and Women, cause she is a slut, so probably not Bi.