Not sure where you got that idea from, but it's pure nonsense - seriously, look up the science-, and contributes to bi-erasure, which actively harms bisexual people. (It's also a really weird statement from a person who currently identifies as "pansexual.") Bisexuality is a real thing. I've dated plenty of bi/pan women who were into men and women, I know bi/pan guys. No, they aren't "confused" or "experimenting" - they are strong in their identies and just happen to be attracted to people of more than one sex.