I never said bisexuality is everyone's cup of tea, just that most people don't have an easily defined sexuality, even if they pretend to others or themselves that they do. Why the obsession with labelling and limiting people?
I call myself straight but I've had more same sex encounters than some gay and bisexual people I know. I know gay men who've slept with more women than a lot of straight men I know. Maybe a few people have straightforward sexualities but that's unusual, and more and more people acknowledge that fact.
I suspect most people are pansexual really.