> I'd argue that we see lots of decentralization on the web.
Youtube, Paypal, Facebook, Steam, Reddit, Medium, Github, hell even hackernews - I think the big success story of the internet in the past decade has been the centralization. Decentralization is usually popular because of illegal intents (like bittorrent). I agree with you though, they could exist in a hybrid state and there will always be markets for decentralized systems. But a global economic system run that way is on a totally different scale and stake.
> I'd say that money should definitely be decentralized.
Depending on how it's done, it very well should, but a lot of things come into question like governance and consumer protection, and actually moving the world forward and helping those who aren't computer savvy. Unless you're a libertarian, the economy is really a means to an end and not and end in itself, and another big success story over the past decades has been the huge global economy that has been created and enabled everyone from the poor to the old to people who aren't as savvy to work and live relatively safe lives. You can't just dump the bitcoin software on everyone and say, "here it is! your life savings, your paycheck, your everything, just make sure you don't fry the hard drive that it's stored on and make backups!"
Decentralization is for the most part, an enthusiast endeavour. The centralization aspect is powerful because it offloads all the technical details so that 5 hours per day of brainpower on the whole globe isn't wasted on just trying to do something as simple as recovering 5 bucks in an emergency. And this applies to almost any decentralized service and applies even more strongly to things that are of survival importance like money. I'm not disregarding the idea or making a prediction, it's just there's a lot here to think about I think