So the devices probably go across the WiFi networks they're on and hack into the owners' PCs (or phones?) to mine Crypto-"currency"... At least that's the one way I can see for it to make financial sense for the manufacturer.
The manufacturer earns money by selling the hotspots, so not sure what you mean tbh. I think wat you are describing is a anti virus scheme like Norton 360 and Avira are doing by install/hack into PCs with hidden PoW mining code which is unethical/horrible . Bit weird to claim this for a hotspot that hasn’t a connection to your PC and trying to slander something without investigating it properly. I get the blockchain hate (especially PoW), but unfair to accuse every project of unethical behavior if there is no proof whatsoever.
/cynicism