Along with that, the cost to "develop" the miner is pretty much a fixed one time cost and they just have to hit a few deploy buttons to do it. The software to do the mining, and send the tokens off to where they need to be already exists and can be sent to tons of different places to do the mining (CI infra, hacked AWS accounts/EC2 servers, etc.). There's very little overhead for them to actually get the things running.