Most public Fediverse servers are running on professional hosting services using business-grade data centres. They are owned and controlled by grassroots admins, but they are on the same kind of hardware as commercial online services.
For some reason there's a misconception floating around that all Fediverse servers run on home machines in a corner of someone's living room. This usually isn't the case. It is possible to do, but most admins don't do this, especially not for public servers.