I do not think that self-hosting necessarily means that you have to host it at home. As others have pointed out, its more about hosting it on hardware you control.

I do think there is certainly a trust factor involved if you host stuff on hardware that you don't own, but at the end of the day only you can deem whom you can trust. For example, I rent a couple of dedicated servers from a provider, but I also have a pretty good personal connection with the owner of that provider - so I have no concerns about the safety of my data. In general, I tend to just be pretty conscientious about what data is going to any server, and anything that I wouldn't want falling into the wrong hands doesn't leave my house unless I can guarantee its safety (with the likes of encryption and such).

I do also keep in mind that with the various providers out there, reputation is paramount to them (or at least, the good ones) so it is generally in their best interest to say, let someone walk into their datacenter and just start ripping the drives from your systems.