Logician, yep. I wouldn’t really like to turn this thread into one of our slightly off-topic discussions, though they are definitely enjoyable. But I’ll just say this:
I very much agree that having a non-realistic over-estimation of our abilities isn’t practical. But at the same time, it is a fact that a positive attitude is many times all that it takes to get through a nisayon, and is, at other times, the “x-factor”. So, for a person to lack the confidence to get through a nisayon, which, as you’ve said, can cause enough negativity that one is unable to even admit it, that itself can, and usually does, cause one to falter and stumble. So being too “realistic” can even BE the cause of not getting through a nisayon. Bottom line: I say it’s better to always have the confidence to make it through.