It's tautologically true that for any X, if you don't try to do X, you won't succeed. But, you also have to weigh whatever good may come of success against the probability and potential consequences of failure. In cases like these, you're by definition dealing with someone who is a little off mentally, whether that's just a temporary condition (e.g. having a bad day), or serious mental illness. Such people can tend to be unpredictable as a result, which is dangerous in its own way.

So, yes, I agree with you somewhat, but I think the balance of consequences tends to favor not acting in cases like this rather than attempting to do anything.