This is a general purpose PC but it's also designed for Steam. Valve will get back a fair amount of revenue on games sold for usage on said machines. They could sell it with little to no margin (maybe they are doing it) while increasing gaming time and potential revenue. Sure, games can be had for cheap and so far it seems to be profitable.

If they were sell it without margin people would buy it as a general purpose mini-PC.

Spec may not always match your needs. The hardware is tailored for PC Gaming which is dominated by Steam.