But they get to enjoy both the social proof on SO and GPT-4 existing.
It's not like they're getting validation from most readers anyway. People who vote and comment on answers are playing the SO social/karma game and will continue to do so whether GPT-4 exists or not. Conversely, people who'll find answers via an LLM instead of viewing it on SO are people who wouldn't bother logging in to SO, even if they had accounts on it in the first place.
People are complaining about losing the audience they never had.
Yes, it's hardly surprising that people find upvotes and direct social rewards more exciting than being slurped somewhere into GPT-4's weights.