http://blogs.reuters.com/felix-salmon/2012/05/07/how-venture...
And given that VC returns tend to be based on a small number of long tail hits, I have no idea how you could say "risk has little to do with it".
It is true that the VC sector underperforms. That is because the lower tier firms are just pretenders. They are funding second tier companies, and second tier companies are not good enough in these winner-take-most markets. These firms should shut down and limited partners should stop burning their money by investing in them.
My disagreement with Piketty (judging from the summaries - I haven't read him yet), is that the cause of inequality is not capital versus labor. The cause is the rise of winner-take-all-dynamics, which causes stratification within sectors.
The high returns entrepreneurs and investors can receive is a result of capturing winner-take-all market opportunities. Mark Zuckerberg, for instance, took very little risk in the scheme of things. I heard a talk by a Sequoia partner once. He said that their investing philosophy is pretty simple: Look for billion dollar market opportunities, and invest in the team/company most likely to capture that market. Thanks to Sequoias's reputation and contacts, they can attract the top entrepreneurs and thus earn extraordinary returns. Risk has little to do with it.
Much of the risk in startups actually comes from the fact that the market opportunities are usually pretty obvious, so there are a bunch of startups competing for the space, and only one or two can win. There are some entrepreneurs who take on genuine technology or market-existence risk, but this tends to be the exception these days.