Popular sites like
https://freebitco.in/ are supplying us smaller and smaller each time. Is bitcoin slowly becoming rarer and rarer? I just started mining. So I hope that can help me. Please can someone answer this?
They are depending the amount of your cash out with the price of bitcoins. Bitcoin is not becoming "rare" at all but rather becoming expensive. Back then, there are still faucet sites that offer much decent amount than a regular faucet site. Today, there's not much around.
This small amount of money is the only amount of money that they can pay to you for increasing the traffic on their website, and maybe even for clicking one of the ads on their website. They are earning quite little on their website so they are paying much little than that.