Because they are useful as a form of money. In the case of Bitcoin, this can be measured by its growing base of users, merchants, and startups. And as the digital age continues to dominate, a currency that is built on the Internet and for the Internet, especially one that requires no third party and can be programmed, it just shows the potential of Bitcoin. But the truth is, it's not really that expensive. The actual price isn't really a true reflection of its value. It's the market cap, and that is just over $200 billion today. A lot of money to me and you, but as an asset, $200 billion is tiny.