I recently stumbled over wallrewards.com, a site that offers you 20 Satoshis per solved captcha, without any time limits. If you solve one captcha per second, that adds up to 72.000 Satoshis (2.88$ at current prices) per hour. Way more than any other faucet site. Why would someone give away so much money?
At first I remembered about those captcha-farms, that employ people to spend all day solving captchas for shady companies that want to create huge amounts of accounts on different platforms to use them for spamming or other malicious activities. What they are actually doing, is quite close to my initial thought.
They simply channel the solved captchas through to another faucet that is even more lucrative to earn money for themselves: The Raiblock-giveaway. It is basically an coin-airdrop to advertise a new micropayment system. (Definitely worth checking out!)
It turns out that they are earning about 13$ in XRB coins per hour by using your solved captchas in someone elses giveaway and are giving you 2.88$ for your hard work. Doesn't seem as good of a deal now, does it?