Did Captcha ever make any money?
First, Luis was not making any money of captchas. He was just an academic, happy that someone was actually using his creation. Later, he ended up building a small commercial version of captcha and selling it to Google, a product that became the Google Image Labeler.
By 2006 however, captcha was widely used on the internet, and this time Luis started a massively profitable company called Recaptcha. Every time someone was typing in a short segment of captcha, on the back that action was actually digitizing printed text. Meanwhile, companies like New York Times and Google were paying Recaptcha for every input.