Let me talk about this explicitly; this is #marketing 101 and story writing.

If people are HAPPY, FULFILLED, and HAVE A PLAN, the subtext is "these are people you want to copy."

If people are MISERABLE, STRESSED, and HAVE NO PLAN, the subtext is "never do this." https://twitter.com/moritheil/status/1359243664803966980

This is why, when you are selling a service or product, you have to show your customers HAPPY, or BECOMING HAPPY. And it is best to show that even when they were unhappy (before hiring you) they HAD A PLAN.

Why was the net effect of the 90s "gritty" heroes to turn people away from heroism as a concept?

People generally do not enjoy reading stories of misery and suffering. Particularly when "good" people suffer. On some level, they like to think they will be rewarded for virtue.

And why was Stan Lee's "fight for a world that hates and fears you" idea of heroism ultimately self-annihilating?

Well, who wants to put in effort and still be hated and feared? Most people would say, "I might as well not show up!"

After all, who wants to be a sucker?