Comment by ndriscoll

Also very subject to wildly unstable market dynamics. If it's profitable to mine, they'll want as much capacity as they can get, leading Hetzner to over provision. Then once it becomes unprofitable, they'll want to stop all mining, leaving a ton of idle, unpaid machines. Better to have stable customers that don't swing 0-100 utilization depending on ability to arbitrage compute costs.

I wouldn't be surprised if mining is also associated with fraud (e.g. using stolen credit cards to buy compute).