Why I am not on social media

You already know why, I suspect. But just to spell it out:

Short-form social media, by its nature, encourages people to post their most provocative, emotionally-compelling shower thoughts to the world, before thinking them through. It rewards this behavior with attention and social interactions. The more controversial the post, the bigger the payoff.

If you reside in this milieu for any amount of time, you start to think in tweets. When you have an interesting thought, your next thought is about what other people might think about it, instead of whether the idea is any good. You start to simulate bits of the hive mind in your head to predict the payoff of any given post.

This is a gaping personality security hole. When you simulate social media in your head, you're essentially running untrusted software on the most important machine you own. The brain does not have a fair scheduler; the more a process runs, the more often it tends to get scheduled. Your choice of what to run today influences what will run tomorrow.

Watch your thoughts; they become your words.
Watch your words; they become your actions.

—Buddha

This feedback loop is inherently, structurally toxic. It doesn't matter if there are no algorithms. It doesn't matter if there are no ads. It doesn't matter if the CEO is not a berserk fascist billionaire.

If you're on social media, you're part of someone else's botfarm.

A difference of degree

Even if you're not on social media, the thought patterns I've described above will happen to you from time to time. The only way to completely escape, I surmise, is to stop thinking in human language, and live entirely outside of society and culture.