There’s plenty of room for idiotic behavior within the broad category of consensual sex.

I know what you’re saying but an adult can consent to smoke cigarettes and that’s idiotic behavior. An adult can consent to eating fast food every day and that’s idiotic behavior.

So maybe consenting adults having unprotected promiscuous relationships with numerous people they don’t really know within a community that “shares” is idiotic behavior too.

That's a little facile.

Quantity has a quality all its own, and so it is here. It's having lots of sex with lots of other consenting adults, whom you do not know particularly well, unsafely, etc., that pushes it into "idiotic behavior."

looks at number of aids deaths. It depends doesn't it?