Doesn't Stefan pay for the npcserver to be hosted on a computer or something?
Also he pays to host your playerworld?
Plus he allows you to use Graal Level Editor etc. For your player worlds which could take away from his general worlds (most good p2p playerworlds are pay though so that isn't really a problem)
But you should also factor out the costs for hosting your playerworld.....right?
If you wanted to make money off this then just buy a license
hehe