I've already laid out why it has worth, so no need to try to explain it again.
FBA makes it a cryptocurrency because the coin employs cryptography to come into existence,
Actually FBA does have something to do with blockchains, because transactions are recorded on a blockchain.
The inherent worth is in the value that it is given by those that participate in it. If people exchange something, then it has worth. That's just the very definition of something being valuable. And additionally, the coin is going to be on an exchange, so it will be compared against other coins and fiat, so it will then have monetarily measurable worth as well.
Existing cryptocurrencies are parasites because those that run them want them to be that way so they bring in huge profits. It's not an inherent feature of cryptocurrencies. It's an inherent feature of human behavior.