Won't forking the chain randomly decrease the value of a particular asset?
Why?
If it's hard fork no one cares about the market impact is close to nil.
If there's a market impact then people care about the hard fork, in which case we can assume that there's likely some merit to their approach.
Historically speaking hard forks caused price increases at least as often as they lead to price deprecation, if not moreso (e.g. the impending BCH and B2X hard forks lead to a run up on BTC's price, the impending BSV BCH hard fork... not so much). In conclusion the market impact is pretty much unpredictable,
if there is one (which in the case of the numerous Bitcoin hard forks was relatively seldom).
Don't you think we should have like a committee of people who gets to decide if a blockchain has to be forked or not?
If a committee of people could decide on who forks off and who doesn't we'd lose a major aspect of the freedom and permissionlessness of cryptocurrencies. No one is in control, and that's the whole point of it.
In practice it's the free market as an extension of our community that decides which fork becomes successful and which doesn't. You don't need a committee for that.
Note that I'm talking about "independent" hard forks. "Sanctioned" upgrade hard forks are a wholly different thing (e.g. the one that Vitalik has in store for Ethereum). In this case you don't just "randomly hard fork" off the main chain but rather have a developer team that orderly decides on a course of action (e.g. the switch from PoW to PoS) and -- optimally -- a community that supports this decision. Or not, in which case parts of the community can fork off and see whether their approach is more viable.