Genesis is probably not a ponzi scheme but i doubt that they are backed with 100% hashing power anyways. Also even if they were doing what i call "full reserve mining", their track record of producing profits is just not very good. I'm pretty sure though that their mining farm/operation has been confirmed by some guy on youtube that visited it, though i don't know if that many miners backs up the  whole amount of contracts.

Many people get their mining contracts terminated before they even make a ROI.

So yeah, do your own diligence as always. And of course, avoid the obvious phishing sites like the site you got in OP.