> Since we started it in 2005 we've funded about 6500 companies.

> I've spent the last 21 years training people to become billionaires. So far about 30 of them have

Since it's a post about math, let's do it.

6500 companies with 2 founders each - 13000 founders.

30 of them became billionaires - 0.2% of them.

So being a tech founder at the most famous startup accelerator in the world give you about 0.2% chance of becoming a billionaire.

Or put another way, only 1 out of every 500 YC-combinator founded startup makes one of it's founders a billionaire.