AFAIK comprehensive numbers for YC outcomes are not public, but Paul Graham has indicated that returns from YC investments follow a power law distribution, mean

AFAIK comprehensive numbers for YC outcomes are not public, but Paul Graham has indicated that returns from YC investments follow a power law distribution, meaning that if you can only get equity in a single YC company (by virtue of being an employee) you have a very small chance of making a ton of money but probably will end up with very little.