There is a large difference between asking someone to name a price and asking someone to donate. In the first case you are forcing them to pay for a product (even if they pay $0). In the second case you are hoping they feel charitable.
The Humble Indie bundles come to mind as a nice way for people to name a price, given their popularity I'd guess they are doing something right.
If you had a human driven car, would a malfunction in the car causing a crash be your fault? [1] I can see that if you hadn't updated the firmware of the car then maybe it could be claimed that you had not performed adequate maintenance?
I don't know if 'bitcoins are being created every day' is the right way of looking at it? Bitcoins are more discovered as opposed to created. It would be like if every USD ever was buried and people were gradually digging them out of the ground and everyone knew exactly how many were buried? The amount of bitcoins in circulation is increasing but the total amount of bitcoins that will ever exist isn't increasing at all.
Relatively few linux users might have a gtx 680 but there are a large amount of windows gamers that have a card similar and may switch to linux if it had steam. Given that 60fps is all that's required it also means that you don't need a gtx 680, a $200 card will probably easily get you 60fps, a lot of the nvidia laptop cards will also probably be enough.
I find it interesting that people's main concerns are the privacy laws. Isn't anyone concerned that there is a need for gunshot detection? I would have thought that the main issue was that there was enough gun related violence to make this product viable? As much as I love to see an innovative solution to a problem this seems a lot like its treating the symptoms and not the cause.