Is it possible that bisexuality is treated more as a "choice" than homosexuality or heterosexuality (Please read details)

Of course some people still believe that homosexuality is a choice.
Of course some people accept everyone, as they are, regardless of how they got there.
Of course every group of people, whether classified by sexuality or otherwise, deals with their own unique struggles.

Having said that, I was discussing this in PMs with another jelly, and we are both curious to hear opinions from the collective on the subject. Some of the stereotypes that I have noticed surrounding bisexuality are that it means a person is greedy, promiscuous, wishy-washy, and/or unable to commit.

I, personally, have met several heterosexual and homosexual people that refuse to date someone that considers themselves to be bisexual. (I’m not trying to insinuate that it is the norm.)

Do you think that bisexuality is less supported in the LGBTQ community than other groups?
Do you think that certain people are more inclined to stereotype bisexuality as a choice, or an act of promiscuity, over other sexual preferences?

Any other comments or thoughts on the discussion are welcome, I am getting a headache from trying to articulate this very carefully, so I’m leaving it at that.