While a pithy thing to say with some truth in it, I have experienced people asserting things of the order of 2 + 2 = 5, and given the right situation it can have the potential to make people pretty mad.
Which is why they revoked your math license, we know the story.
No, when you say 2 + 2 = 5, you can put it off as "He can't be serious", and then it's off your mind. But if the person keeps asserting it till you can't brush it off anymore, that's when heads tend to roll. It goes against what you believe, and subconsciously, that goes against you as a person.
