Even disregarding privacy concerns (which you shouldn't!), I stopped posting on social media largely because I'm too argumentative of a person for it.

When arguing is limited to people I see in person, it's a somewhat time-boxed and constrained operation. I typically can only argue with one person for N minutes, and eventually both of us get tired of it and we move on with our lives, but there's always someone wrong on the internet, and a lot of those wrong people love to be wrong publicly on social media. I would always end up arguing with a stupid post that a stupid person on Facebook had, and then someone would chime in in support of me or the person I'd argue with. Before I knew it, a not-insignificant percentage of each day was being dedicated to responding to idiocy on social media.

Eventually, it started getting annoying and I deleted my Facebook, and never really looked back. I run a Mastodon instance that I almost never use (but I had to justify the server I bought somehow), I briefly worked at Reddit, and obviously I post a bit on HN which is basically social-media adjacent, but despite all this I never really felt compelled to go back to constantly posting on social media.

I suspect a lot of people have come to similar conclusions. I enjoy talking to my friends, and I do pretty liberally on Signal, but I feel that's sort of in a different category than "social media".