The problem is that the two possible causations can and very often are intertwined.
If you personally profit from something, then it becomes very hard not to fall victim to massive confirmation bias, where you want something to be true, and any evidence that supports it is viewed favorably while anything to the contrary is held to impossible standards.
Let's be clear here. He's not saying "do this, it's in your benefit." That would be cause for skepticism because Mark is a VC in competition with other VCs. What he's saying here is that some firms engage in a particular type of unethical behavior. This is reporting on an industry trend. It's even a falsifiable claim despite the fact that we are tremendously unlikely to have access to the information that would confirm or refute his claims.
If you personally profit from something, then it becomes very hard not to fall victim to massive confirmation bias, where you want something to be true, and any evidence that supports it is viewed favorably while anything to the contrary is held to impossible standards.
The easiest person for you to fool is yourself.