Those companies can be fantastic environments to grow and learn. Not everyone knows at 21 that they want to be an entrepreneur, much less has a great idea that they want to pursue.

Muse uses technology to tackle very traditional industry-type problems - career planning and recruiting. A team with a combined 5-10 years at McKinsey and the exposure to an international network of thousands of very smart and career-driven people (plus lots of client companies) is exactly who you would want for this kind of company.

Yahoo and Google were started by PhD students. AirBnB by designers. Marissa Mayer planed to start with McKinsey, Sheryl Sandberg actually worked there (and in politics). Peter Thiel was a lawyer and derivatives trader. Marc Benioff spent 13 years at Oracle.

Why all the hate for people who have not dropped out of college / have worked in another industry? Clearly great entrepreneurs come from all sorts of backgrounds.

I wouldn't say they're risk averse. This is the second company they've started and they're 25. Bonus: Educated at top-level schools and companies.

This is one of the best YC applications I've seen. Smart people working on a huge opportunity that they understand and have some traction in. Numbers and initial strategy suggest they've done their homework and can succeed.

This is exactly who YC should want.

"not people seeking the shelter of Google, McK, Bain, etc."

It seems that by leaving such companies to form startups, such individuals would represent the very definition of 'risk-taker'...

I suppose you could substitute "risk-takers" for "scrappy" since risk-taking is inherent in starting a company. I would say that scrappy is more indicative of someone who is entrepreneurial without necessarily relying on a strong background or network already available to them (since the use of risk-takers has received some backlash from some commenters).