You can read more about roproxy specifically here.
They may not be paying for it, though, if they are, its probably just to help people out.
Plus they would probably be helping themselves too.
This proxy only works with roblox API urls so it won’t work for stuff like discord.
If you want to use a proxy to access other sites like discord, I suggest searching for other proxies here on the devforum. Just be careful not to click sketchy urls.
If you want to learn more about what proxies are I would suggest reading about them here.