If there's a compromised machine, the scammer can drain the victim's bank accounts and cost them far more than an electricity bill, and/or mine cryptocurrency directly. Regardless, their spam-sending rate will still be significantly decreased.
> If there's a compromised machine, the scammer can drain the victim's bank accounts […]
Not if the machine is a server and was gotten into via (e.g.) a bug in a web app. I don't know about you, but I don't keep my bank account information on the LAMP systems I sysadmin.
