Unless the competitors increase the whole market (increasing total value) or—as is plausible with a cryptocurrency with netomwork effects—the lack of a single clear choice reduces the overall value of the market compared to a don't clear choice that everyone uses.

Yep. It might not be zero-sum.

Not quite like a stock split. In stock splits its almost guaranteed that the total valuation is similar.

This is wild, wild cryptoland. At the moment both Bitcoin and Bitcoin Cash are rising - so a lot of "free" money (at least in the short term.).

For now, two coins is better than one :p

EDIT: allright, Bitcoin Cash has been declining for a few days now. However, it still has quite a bit of value that has not disappeared from Bitcoin's value.

Rationally, though, the increase should have happened anyway. Fair point about crytoland though :)