I run my own instance, the benefit is privacy and reliability. Everything is controlled on your own server. You also aren’t reliant on someone else running an instance that could go down at any time, either permanently or an outage. Been a problem with Lemmy.ml recently.

For me the benefit is uniformity (not sure if thats a word) i can have a matrix account, a mastodon account, a lemmy account, all sorts of fediverse accounts all under my own domain.

This comes next to the already mentioned benefits ofcourse :)