Cryptocurrencies are technology, but their value comes from a "social contract", people agree that the "asset" created by the blockchain is of some worth. You can take the bitcoin code, make a copy, change a few parameters and rename it to "myCoin" and sell those coins to your friends, but there would be no social contract in place to give it value.
Cryptocurrencies dont HAVE to be decentralised, they can and probably will be issued by governments in the future (and I suppose Venezuela has already), bitcoin is what is called a "permissionless" crypto, meaning you don't have a central authority to appeal too if someone steals all your coins, but "permissioned" cryptocurrencies will allow a central authority to have the final say, think about land tokenized onto a blockchain, the local government in charge should be administering it, and your land shouldn't be able to be stolen from out beneath you like bitcoin could ("sorry mom, we have to move, Bob got our private key and stole our house"). Also, bitcoin can't be inherited without making plans to specifically do just that, think about the Canadian crypto-exchange that lost access after the guy in charge died, no one had access to the private keys, so no court could make a ruling to move the money, cause it's not possible without the lost private keys.
Technically, Venezuela issued their own currency, but the trust is not there in the government, so that lack of trust extends to their self-issued cryptocurrency as well.