I'd be curious to know how the economics of craigslist works, such that he's made so many hundreds of millions of dollars. It only charges a modest fee for a small fraction of transactions, but presumably the denominator is big enough that this adds up (and of course he would have subsequently invested the proceeds).

I had assumed that the fee portion of the site was substantial enough to cover all costs, and generate perhaps tens of millions of profit (he's well known for having given away money to media, so obviously there's some profit). But I didn't realize that it made hundreds of millions of dollars.

Are there any articles that break down how this pencils out?