No government in the world will be happy to give up their power to control the currency. Exception being El Salvador which is now facing a crisis because they adopted Bitcoin at a higher price and as it fell, well so did whatever amount the government and their people had purchased.
As a currency, it is too volatile. The main reason that currencies of large economies aren't as volatile is because the "evil" central banks intervene. If there is too much inflation, they can raise interest rates, open market operations to reduce Liquidity etc. and vice versa.
As a storage of value, it is well known that you shouldn't be keeping your money as cash or in a savings account because of inflation which btw is quite necessary for economic growth (controlled inflation). Rather wealth should be stored in real estate, fixed income instruments, equity etc.
If crypto is unable to fulfill these two things, what is it then ? A failed idea maybe which people thought of as a get rich quick scheme.
Moreover, people keep talking about whales, so however decentralisation there is, power would automatically flow towards the more influential and rich anyways.