I think there's an option - there's something you can do to alleviate these issues that you may be unaware of.
You are noted as having uniquely horrible experiences. An impartial observer would conclude that one of two things is likely:
1) There is something you are doing that is contributing to these problems.
2) There is something you are doing that is both drawing these problematic people to you and driving away less problematic people.
But one of the other things that's important is that players see the results of their actions. You've complained before that the players say it doesn't matter what they do, the results will be the same... but that's kind of what you're saying.
If you've decided that the PCs will lose 90% of their HP, and then play the enemies easier/harder to guarantee that, then from the player POV it looks like what they do doesn't matter. If they play "well", they lose 90% of their HP. If they play "poorly", they lose 90% of their HP. They can't even tell what is good or bad play at that point.
And this leads to a feeling that their actions don't matter. Which leads to a lot of the type of complaints you get.
Note that a similar "it doesn't matter" issue comes about if you don't give players sufficient information to make decisions - "gotchas" and things like that just exacerbate it, especially if you make them super-aware of the consequences. And when doing stuff like that, try to think of what the players do actually know about the situation at hand - not what they "should" be able to guess or infer from clues you've given them.