I am going to have to respectfully disagree with you on this, Seanandem. And this has nothing to do with having any ax to grind with bi-sexuals, homosexuals, or any other sexual grouping of human beings. And we definitely agree with the last part of your post: Adults are free to pursue their happiness and sexual gratification however, and with whomever, they please (so long as they are other consenting adults, of course.)
However, on the subject of bi-sexuality, it appears you are practicing what is known as confirmation bias and ignoring the mountains of empirical and anecdotal evidence that points in the other direction. Objectively and impartially viewing the world around us would indicate the overwhelming majority of people are heterosexual only. That's neither "good" nor "bad". It's just the way the world presents itself.
Yes, it is possible that billions of heterosexuals around the globe, from all different cultures, are secretly harboring bi-sexual tendencies. But, that seems rather improbable. It is far more probable they are simply heterosexual.