based on your previous answer you are confusing the different types of centralization.
we have fiat that is centralized but it is trusted and used and adopted by EVERYONE. people don't doubt about fiat. it is legitimate.
we also have shitcoins that are centralized but they are shitcoins, they don't deserve the trust because they are created by a company or some group of shady people who started it to make money. Ripple and a lot of other altcoins fall under this category and that is why they will never succeed.
on the other hand if the government that is already controlling fiat were to release a centralized cryptocurrency that would be a different thing. it will be trusted and used by lots of people because they will see it as fiat.
however that has nothing to do with bitcoin or any other decentralized currency that may exist out there. specially since bitcoin and the likes of it are global and cheap to use while centralized coins (gov-coin) are limited to one country and expensive to use.