There's quite a bit of data on the distribution in the post as well. Quoting from the summary:
Most of the returns have gone to a tiny minority of super-successes. The founders of AirBnB, Dropbox and Stripe are worth about US$7 billion, about 78% of all founders’ equity, although they account for 0.5% of the companies.
Outside of the most successful companies, it was still possible to earn significant returns. 12% of companies from the first five years of Y Combinator are now worth US$40 million or more, and a further 10% have sold for US$5-40 million. The remainder probably earned little more than their (low) salaries.
Most of the returns have gone to a tiny minority of super-successes. The founders of AirBnB, Dropbox and Stripe are worth about US$7 billion, about 78% of all founders’ equity, although they account for 0.5% of the companies.
Outside of the most successful companies, it was still possible to earn significant returns. 12% of companies from the first five years of Y Combinator are now worth US$40 million or more, and a further 10% have sold for US$5-40 million. The remainder probably earned little more than their (low) salaries.