There are like soo many good bls with no 🍇 and all but why are toxic ones so popular? A...

More than the outright toxic BLs (sometimes I'm in the mood for that too, and otherwise I can avoid them without worries) I'm MUCH MORE MAD at BLs that start with a green flag/puppy ML only to have him SA the uke out of fucking nowhere, usually out of jealousy. I've come across so many like that! It was going so well, why do you have to ruin it?? (and lots of times it's not even addressed)

Taking the higher moral ground while they read on an illegal site is crazy i dont like unnecessary rape so i just avoid it but i won't go on a story's comment section knowing the trigger warning and calling the story shit just because of it, the policing has been crazy lately but to answer your question its because they usually have more spicier drama and better smut art than some, i used to read the most toxic shit for the love of the game idc abt the plot back then lol

Srsly answering your question with my own thoughts regarding the matter so it's pretty long:

While I personally don't seek out non-con in stories I consume, I think those kinds of stories being popular can go down to the romanticization of SA/abuse in society and how "dark romance" has been associated to such rather than what it initially was. There are studies tackling that topic actually.

Before I go onto the next point, it's important to state that representation of non-consensual experiences in media can be significant when it's handled with respect and actually gets acknowledged. So some stories that include non-con without justifying it + addressing it's issues can really help spreading awareness.

However, when it comes to the ones you're probably thinking (stories with graphic content that doesn't get properly addressed at all or even gets romanticized), it mainly comes down to people's preferences in fiction as well:

Some people's reasons might be because they find comfort in situations similar to theirs despite not having a proper conclusion, to feel some sort of relation or the thought that "at least I'm better off than this".

Or because they are people who can easily distinct reality from fiction, hence not letting their moral compasses be affected by what they consume.

Otherwise, people just actually do enjoy media romanticizing SA/Abuse, which could be the result of the normalization of it in society due to how it isn't treated enough as a taboo.

There are probably some parts I wasn't able to explain clearly but this is what I could gather with the extent of my own thoughts for now. I do see where you're coming from though, it's sad to think about how rapidly these kind of stories have grown in popularity, despite whatever reason it may have been to garner that much attention.