Is it just up-front cost? I understand that for larger instances because they'd have to setup heftier systems, but even micro-instances seem to rent cloud compute when they could probably get by with port-forwarding to an old laptop.

Edit: I understand that self-hosting is a skill that takes years to learn, and I'm aware that the vast majority of people on Earth choose to spend their time and energy investing into completely different topics. However, Lemmy tends to attract the techy type, so I suppose I just assumed the ratio of self-hosters-to-not would be higher. I'm not saying it's trivial, just that I presume more Lemmings know how to do it than, say, Redditors (taking total users into account ofc)