Bitcoin is based on a big assumption that people behave rationally - they do things to maximize their profit while avoiding operating at a loss. But what has been happening recently is that some people are willing to take losses - in a form of spending their money to pump and promote Bitcoin forks, for a long term chance to take control over Bitcoin. For them it's like a risky investment, so to defend ourselves against it we should make it as unprofitable as possible - we should never buy any forks, only sell them, we should also educate others about how forks are just fake coins. Lastly, there's always an option to switch PoW if majority of miners will go completely rogue.