It is impossible to create a decentralized cryptocurrency because it has already been created.

So, the fact someone created something means you can't create another thing of the same nature.

I hate to ask you that, but you're trolling, aren't you?

No. See https://news.ycombinator.com/item?id=36952101

That is a silly argument. Guess you also think there only exist one fiat currency because it already exists one so there can't be two of them?

That is the silliest point of all, because the concept of fiat currency is inherently associated with its plurality (given that fiat currencies are born out of countries, and there are many countries), but cryptocurrency, as a concept, came to existence to destroy all fiat. And the only way to do that is via 1 single cryptocurrency: the very first, the only one. And this is better understood once you understand this: https://en.bitcoin.it/wiki/BIP_0300 (which is not activated yet, and might never be; but once you understand its purpose, you will understand this HN thread)