ps: by self-hosting I mean with both a mix of services developed by others(ex. Gitea) and their own(for me it's collAnon.app)
I set it up years ago on the same server I have my static website. Since then I've hired few people and we keep using the same instance and we added a mac runner to it. Upgrades were pretty painless. We see no reason to migrate to SaaS right now.
Earlier in my career I self hosted all kinds of stuff, but these days I prefer to pay and forget about operations side.
As for the services for customers... unless it makes financial sense and you're happy to be effectively responsible for it 24/7 - why would you? Others can do it better and cheaper and you can charge for the initial setup.