When I was really young, around five, I remember not making the distinction between liking girls or boys. I just looked at everyone. And I still do. I knew that I was attracted to both sexes around that time. It was just natural for me to look at both sexes.
Open attitudes are fine.
That's different than just trying things out to be cool and hip and hurting feelings in the process. If a person really believes that he or she is a certain way and it ends that they aren't, that is still different from people who haphazardly walk around saying they are queer or bi, when they have never even kissed someone of their own sex or been in any sort of intimate relationship with someone of their own sex. My cat is psycho. She is weird. She bites me even when I'm nice to her.