Furthermore when it comes to mining, you are depending on the people who sold you the miners not to have included some kind of malware or spyware in the miners. And that the people who built the miners did not use defective chip parts and so on...
Ok, that makes sense to some degree, but then even if we were to assume that the miner manufacturer would go that far to kill their own business, it still does not justify adding more risks to an already risky business model, it's like crossing the traffic light, even when it's green on your side, there is still a risk of hitting another car, that doesn't make it equally as bad as crossing a red light, the degree of risk of both cases is very different.