So I went ahead and did it. I made a new mastodon account and started posting on it (a). Might as well sit and watch while the birdsite burns and light is shed on the fediverse in the mainstream consciousness.
It's been one-or-two days, and I can already see why people are addicted to social media. I get why people shitpost, too. You say some funny words and then wait a couple seconds or minutes or hours and then you see the notification number go up, and each time you do it actually means something, that someone saw your post and decided to express interest in it by liking or following or commenting. Human brains are hardwired to like social validation, and that validation is collected and turned into currency for you in your notification feed. I could get addicted to this.
I never used any mainstream social media before, maybe because I didn't have enough friends to encourage me to do it. I had a phone at age 12 or so, and there's one social-media that I did try, "Amino", which I probably saw in a youtube video or something (a). I was only there for a couple years, and that's basically my only interaction with social media. I did make some long-lasting friends there, though.
Mastodon seems like a fun place to be if I don't overdo it. I don't think I'll want to dive too deep into it though, since basically everyone agrees that social media can be pretty bad for your mental health if you use it too much. I think if anything it's a useful tool to find interesting people.