Why Is Biphobia Still an Issue in the LGBT Community?

Yesterday I was reading an article on Qweerty all about celebrities that have not come out as gay yet. There were the usual (and expected) list of characters like Kevin Spacey and Tyler Perry.  Now my initial issue with this post was my objection to outing people.  I sincerely feel that people will come out of the closet if and when they are ready to come out.  No one else has the right to out someone before the individual themselves wants to do so.  I am a huge advocate for people coming out and living their lives authentically, but they must do so when they are comfortable enough to do so. 

My biggest issue with this article had nothing to do with its content.  I made the mistake of reading some of the comments below the post.  That is never a good idea if you want to remain sane and happy.  Someone mentioned that maybe these celebrites are not gay.  Perhaps they have not come out as gay because they are bisexual.  And that's when the claws came out.

One person claimed, "There is no such thing as bisexuality.  They're just people afraid of admitting they're gay."  I was not surprised at all by the number of people that jumped on the comment section and started belittling and berating bisexual people.  Bisexuals (who are supposed to be an included segment of the LGBT community) were accused by gays as being confused, greedy, and in denial. There is a blatant refusal to acknowledge the fact that people can be genuinely attracted to both sexes. Because they are exclusively attracted to one gender, it is simply impossible for them to accept the fact others may be attracted to both male and female.

I don't understand why people feel they have the right to define others.  If someone tells me they are attracted to both sexes, then they are attracted to both sexes.  Just because I only like men, I cannot then exclaim that because this is my reality it must be the reality for everyone else.  So here we are as an LGBT community attacking members of our community because of who they are.  Isn't that what we want people to stop doing to us?  Unity should be out goal.  And if we continue to dismiss bisexuals as if they do not exist, then we are no better than homophobes that want to strip us of our rights and deny us equality.