The miners were the ones who helped create Bitcoin Cash. Why would they attack it?
The miners are the largest supporters of big blocks, so it make no sense that they would attack the thing that they helped launch.
Also, people don't seem to realize that it is already possible to do a ~20 percent selfish mining attack. And yet we don't see THAT happening...
These attacks aren't realistic in practice because it would be immediately obvious that something is happening, and the miners would lose all their money as Bitcoin crashes.
* a miner losing its share in the competitive game could make a one last money grab before its hardware is obsolete
* BCash backing miners losing confidence in success of BCH could just damage the whole space, for revenge or and profit
* complete outsider like an angry government could try to disrupt the space to ban all crypto or at least heavily regulate it / buy some time
> BCash shares hashing algorithm with Bitcoin. That means any hashing power on the Bitcoin network can work on BCash network. And there is typically 10 times more miners mining on BTC, than on BCH because of the difference in the price and minning fees.