Why does it matter if bitcoin cash over takes bitcoin, if everyone who owns bitcoin got free bitcoin cash coins? If bitcouin cash will be valued more, you will still have the money.
Because it is a coin made by miners, for miners. It is under centralized control, rejects modern scaling methods that would undermine their control, and frankly can't scale adequately to go mainstream as a result. The last I heard of their great development plans it consisted purely of a willingness to bloat the blockchain as often as needed and literally nothing else, which will lead to just a handful of data centers replacing the current node network.
Do you really want Bitcoin Judas, Fake Satoshi and Jihan Wu as the effective dictators of your favorite cryptocurrency? (Or perhaps a Chinese government behind them?) The notion that Bitmain Cash represents a serious cryptocurrency much less a market leader is both ludicrous and alarming. If cryptocurrency users are going to be that naive then I wish you well but don't expect it will turn out that way. In the meantime I'll rally to litecoin or whatever is left of Satoshi's real vision for a free and decentralized cryptocurrency able to grow to serve humanity. Not miners, not governments, and not greedy or power-mad early adopters.