The userbase is small relative to Facebook and Twitter but I've seen claims that Mastodon has two million active users right now. Also you don't have to host your own, there are sites with shared hosts (many people using one server). Some are free, some have monthly fees.
I've read Mastodon posts but haven't made an account anywhere or run my own yet.
I've been on Mastodon since November 2018. I'm on the mastodon.xyz instance. You can find more information about it and instances on mastodon.social (the original instance which is now invite only). If you scroll down to "Sign Up" on there, you'll see a list of instances that might be of interest to join.
n_n wrote
The what?