scarcity != value. there's a lot of scarce things in the world. it's valuable because it can be exchanged for $$ dollars and there is currently a supply of people who want to make $$ dollars willing to buy it so they can make $$ dollars.
Discussion
I said most valuable AND most scarce. And it's valuable because it's the BEST money ever created/discovered by humankind. Money should be the most salable good, and the highest form of economic energy, and this is what Bitcoin is.
Permissionless, unconfiscatible, decentralized, finite supply, divisible, massless, and travels at the speed of light. US dollar has the last two qualities, but pales in comparison in the other aforementioned aspects of a superior money.