Blitz3D it is possible to buy in shop for ~2 $
Physical version has a disc and covers + someone has to get them to the shop -> raw material and labour: $2 [and it's still not LEGAL version of Blitz]
site host links to a free copy of the full version
Electronic stuff is nearly free to distribute and produce and they probably get ad income for the traffic the warez creates.
Basic "101 how commerce and e-commerce work"...