Everyone is looking at this wrong.
The idea is aimed at those who do not have the PC to play modern games. Now the investment alone for a decent gaming rig is huge. Then what if you decide that it's just not for you?
The idea of giving these people access to ultimately a try before you buy rental scheme is great. Anyone who isn't a gamer will probably take a while to use those 20 hours, and if it is something they go on to enjoy, they will likely choose to build/buy their own rig, and what's better for nvidia is that rig will likely feature an nvidia GPU as that is what they have been using in the cloud.
I can see this being a worthwhile investment by nvidia to bring more people to the PC gaming market, which will ultimately make them a lot of money if it succeeds