Just because something can work in a decentralized fashion, doesn't mean it will when left to its own devices. Generally speaking, decentralization is inherently inefficient. And competition creates pressure to be efficient. You can see it with Bitcoin as well. Just because the network supports it, doesn't mean players won't gravitate towards each other.
Personally, I would never trade normal currency and a bank account for Bitcoin. For me, it does its job very well and at almost no direct cost. I understand that, for example, producers of pornography like cryptocurrencies because they have a long, troubled relationship with banks and especially card companies. But I'm not getting what is the problem of the average Joe. I know, I know, inflation. All you've got to understand is that money is the working fluid of the economy. It doesn't exist to store wealth. It exists to simplify trade. Nothing is perfect. The strength of money is liquidity. You could say that it's too liquid and leaks. :-) There are plenty of ways to store wealth. Each with its own strengths and weaknesses. Choose your poison. Bitcoin was an interesting project, but I don't think its author ever even hoped for such success and I don't think it's fit for purpose. In a way, it was naïve. But Jack is out of the box now.