I have my Mastodon instance broken out into docker containers running on one of my “beefy” servers in my homelab. I don’t regret setting it up at all, but I’m glad I’ve resisted lemmy/kbin/etc. With Mastodon, I don’t feel any guilt about keeping it to myself, and having no anxiety about someone losing content. I tend to feel like if someone is creating content on a platform I own, I have an obligation to treat it with respect, as opposed to how I feel about my own content.

Here’s the (excellent) guide I followed (mostly).

I think you hit on one of the key points. Every other time this same pattern has played out, each of those sites becomes a shadow of what they once were, but the continue because (to be blunt) running Internet sites is CHEAP.