As a bisexual guy, I will throw in a second confirming anecdote.
Theories of sex decreasing because of men being left out of the economy, the secular decrease in testosterone, men being addicted to video games and porn, etc. have to grapple with the likelihood that casual sex hasn't decreased among men-who-have-sex-with-men but rather increased. If that were confirmed, then why are men-who-have-sex-with-women in particular not having sex?