Because good VCs make money on the ones that successfully monetize, not on consistent 10% ROI. That kind of return is great, but just be a PE firm if that's your goal.
If you have the money to play the odds like that then more power to you.
I just don't like the acknowledgement that most of their investments will fail.
Naw man, that's just how it goes in VC world. You have to play it like that. It's like a roulette table -- hard to hit a number but pays out 33x. Well, similarly, a very successful start-up can pay out 100-1000x and easily carry the other losers.