czcastermaster :
you "risk" death just by being alive
also: what could actually go wrong
That's a fallacious comparison. Just like there's always a risk of dying, there's always a risk of a PC breaking, whether it's bare on a desk or in a case. Using the case instead of a makeshift blower enclosure is like wearing a seatbelt, driving on the correct side of the road, putting out a cigarette before you go to sleep, or not pointing a gun at your face.
It significantly decreases the risk of the worst case scenario happening.
Aside from not being able to enjoy your games because of the noisome mini hurricane next to your PC?
1. You'll short the motherboard if it's on a conductive surface.
2. Your cooling might actually be worse, since a plexiglass + dust filter box will still trap heat, and it won't have localized fans over specific parts of the PC.
3. You won't be able to move the PC at all.
4. Your PC will look like crap. And don't try to tell me you don't care about aesthetics, because if you didn't care how things looked you'd be running at 480p, 30 fps, minimum settings, on a GTX 550, and we wouldn't even be having this conversation because without aesthetics there's no reason to overclock in games.