Coins are only as valuable as people deem them to be
Yes - is is purely a fantasy and like all dreams you will wake up and it will be gone.
There will only be one Bitcoin. Bitcoin Cash and Bitcoin Gold are altcoins, much like Litecoin or Ethereum.
Clearly you are driven by a religious belief. "
There will only one god" replaced by "
there will only be one Bitcoin". But as in all religions, people tend to start beleiving the "one god" is slightly different and then you get different gods and wars over who believes in the true god. The recent war between Bitcoin and Bitcoin Cash is only the begining. Ultimately these will all destroy each other and credibility in the cryptocurrencies will be totally gone.