Do I understand correctly? You use WireGuard to set up your own VPN servers? Doing this is a lot more expensive than buying a VPN subscription, but it can be more secure if you know what you're doing, right?
WireGuard is not only about that. Sure you could do it. But it is applicable for any use-case where you have two or more machines that need to talk over a secure tunnel, over an otherwise not proven to be secure network(which is usually, but not always, the Internet). This ranges from connecting to a machine you have at home, to exchanging data between two office branches, and so on.
If you can't trust a VPN provider for some reason or are trying to secure a route to a specific network, setting it up yourself starts to make sense.