That's because crypocurency has very limited uses right now. You need to start spending bitcoin on real stuff in order for it to be decentralized. We are at a catch-22 right now where people don't want to actually use it as a currency because they see the value skyrocketing and don't want to be left behind. At the same time though, everyone hoarding onto it will eventually cause the whole system to crash because it won't have any actual value. The guy who bought 2 pizzas with his bitcoins is mocked for all the potential money he threw away, but a big part of why bitcoin is worth so much now is because he actually showed how cryptocurrency could be used.