There is always risk in investments not just from ponzi schemes, what immediately sets my alarms off is you haven't spotted them yet.
I never said it's low risk. There's quite a few things that can go wrong, eg theft, malware, hacked, significant economy changes.. However, the risk of this should be similar bitcoin mining.
Please quote where I said this has no risk.
EDIT: I also have to build an energy efficient PC with massive amounts of RAM..