There must be some double digit percentage of them who are genuinelly sculpted in specific way in that harsh working environment. Or you are saying that stressor doesn't make you better in any way (if you survive it).
Probability looks higher that you will find such people at ex-Space X group then other more relaxed and/or bureaucratically leaden companies, IMO.
They shower them with money because, as always, they don't know who is genuine and who is not, only results will tell but looks like a solid bet anyway, more then showering with money random engineer of ex anything.
So if you personally see a lot of failures, that doesn’t mean the VC model is failing. Although most VC funds lose money (there’s a power law for their returns too!)
Paul Graham wrote a scathing summary of VCs, and one reason for YC is to be more honest and fair (YC still aims for capitalist gains, they just play the game differently). http://paulgraham.com/venturecapital.html He also wrote that it is near impossible to pick investment winners (which is what VCs are “supposed” to do).