PoW alts are not bitcoin forks..
a bitcoin fork contains the last 4.5 years of bitcoin transaction history, that then takes a different path compared to another.
the other PoW alts DO NOT contain bitcoins history, thus they are not forks. but simply mutated code .. they have nothing to do with bitcoins blockchain and again have nothing to do with 'forks'
you could call them spoons.. meaning the handles look similar and the purpose is similar but they are not the same thing. they were made separately
You are referring to forking the blockchain and I was referring to forking the source code in that sentence. Fork is a commonly used term in open source projects and it is the blockchain which borrows that term. Those can be done independently or simultaneously. If a blockchain snapshot is taken and forked as well than the net effect is people would double their coins but the usability and value of each of their coins would drop significantly. In certain cases the value of both coins compared to a fiat pair would be higher and in some cases lower.
You are incorrect to say that the value of a Bitcoin fork is the value of the combined value of the bitcoin of the participants of the fork. If the market does not give any value to this bitcoin then it will not have any value, and the bitcoin on the unforked network will still retain it's value.
Why are you assuming the new users that follow the new blockchain/fork aren't considered a "market" into themselves that can trade value , services and goods. This market may revert more to a speculative market as many vendors could drop off but it would still be a market which attributes value to these tokens. Additionally, there are possible case examples where a majority of the merchants, vendors and users leave the asic farms behind and make one blockchain heavily secured but worthless (thus rapidly becoming unsustainable) and the other blockchain being initially less secure but heavily valued and thus rapidly regrowing security.