No, ugly gays, fat gays, gaysians, elderly gays, and (in densely populated Aryan-worshiping gayborhoods like WeHo and Chelsea) blacks are the pariahs of the gay community. But bi guys take a lot of crap too.
That in 2013 some gay Internet trolls are still claiming that bisexuality doesn’t exist just shows how entrenched biphobia is. Like racism and homophobia, it’s never going to go away completely because you will always have ignorant, uneducated bigots around.
The Kinsey scale has been around for sixty years and it’s still fairly accurate: most people are exclusively hetereo. The second-largest group (which is not all that large relative to straights) are exclusively gay.
The rest fall somewhere in the middle — but that group is diverse. Most bisexuals are clustered towards gay, and a smaller group of bisexuals leans straight. 50/50 bisexuality is the smallest and rarest group. This is one of the reasons that bigoted douchebags claim bisexuality doesn’t exist — most “bisexuals” in fact lean one way (straight) or the other (gay). The image of bisexuals as a uniform group equally attracted to men and women is not demographically accurate.
Openly bi males in American culture tend to end up living almost 100% gay lifestyles because 1) most bisexuals prefer their own sex, and because 2) it is almost impossible to find an American woman who will seriously date a guy who admits he’s bisexual. Closeted bi males tend live straight lifestyles, out of fear and discrimination. So bi guys tend to be quiet about their bisexuality. Why? Well, those who want a relationship are eventually going to end up “picking” straight or gay for all practical purposes, settling down with either a guy or a girl. So why scare off partners by trumpeting bisexuality?
In my experience as a Kinsey 4, most young, informed, intelligent gay guys I’ve met know they have nothing to fear from open, honest bi dudes — because chances are he prefers men and will end up with one for the reasons above. Of course a clueless minority of gay dudes will continue to spew biphobic nonsense, but thankfully they’re dying off.