Vaultwarden is specifically used for self hosting. Setting up a Wireguard VPN on your server at home can be tricky in specific instances. Most of the time it’s dead simple though. Installing a Wireguard Client on your mobile devices is as simple as scanning a QR code. And to be fair: If you’re going to expose the Vaultwarden instance to the internet why not just use the official Bitwarden service then? I’m sure they can handle security better than someone who has trouble setting up an VPN server.

That’s why most use a VPN.