Basically I would tell that Bitcoin supply and demand
Everything in the world of Bitcoin is about supply and demand â those two basic economic categories.
Following are methods ti earn free btc
1- Visiting websites or doing small tasks
Another way of receiving small amounts of coins is visiting Bitcoin-related websites or doing small tasks on the web. There are numerous websites which provide this opportunity to earn some free Bitcoins
2- To get free Bitcoins fast with Faucets
3- Getting Bitcoins through Trading
Trading is one of the most popular ways to start earning
Summary of my post:-
With Bitcoins being pricy, it is always luring to find a way to get some for free. While some rely on faucets or little tasks they can do for couple of hundreds of satoshis, others find more intriguing ways, such as gambling (where everything depends on the chance) and trading (where everything depends on your prediction skills)