See, that's not gonna work. We can't just write this off as a friendly disagreement when the opinion you're expressing reveals you as such a terrible person. My sister (and by sister i mean my best friend from young times who is basically closer than blood) is bisexual, and I've known and been friends with her SOs of both genders, and you expect me to accept, even not be incredibly offended, that you believe those relationships were insincere because of what some asshole wrote on the internet? There are millions of people who have gone or are going through things you might believe are impossible or fake because they don't jive with what you read online.
Go outside. Experience life for yourself before you make broad, inaccurate, and offensive judgements about anyone else's.