We have a neighbor at our office that has a setup a mining machine at his place. He's doing the Ethereum mining - similar to bitcoin, just a different system.
He's spent about $5k in equipment for mining and says he's doing OK. I've yet to see him pull into the office in a new car
I guess he's on the watch for some new system or rig which can run with even less power but if you chain multiple together you get better processing.
Personally, I don't know enough about it. I prefer to play Craps at the casino. That, I understand!