I'm bi. One thing I've noticed in my life (socially, in recovery and as a counselor) are people who've experienced hard lives and sexual trauma often have their boundaries eroded to nil. They've been numbed out of touch with their genuine desires and many have wound up doing sex work. Many people I've known like this say they are bi because they've had to sleep with same sex partners in their line of work, or they've done so in prison, or for drugs, or they just don't know how to say no to people.

But would they be straight or gay otherwise, if they'd grown up in a safe and healthy environment? I'm guessing some would. I'm not say this describes most bisexuals, I'm bi and know many healthy bi people. But I do think that trauma and mental illness push a certain population into habits and environments where they are pressured to convince themselves they are bi. Like a woman I know who would never seek a woman on her own, but has had 2 boyfriends who insist on her participating in threesomes and swinging and she goes along with it (without liking it) because she has numerous mental health issues and lets men walk all over her.