Exhibit A. This, folks, is just one of the things that can happen to people who take some kind of quasi-religious stance against coffee.
I have nothing against people not liking coffee. Taste is taste, and there's no point arguing about it. But people who try to extend that personal dislike to everyone else? - they can get lost. In a blizzard.
Why is "bitter" an argument against it? You may not like it, but there's plenty of people who do. Can't we both be allowed to enjoy our own tastes?
As for "burn your mouth" - yeah, that's not a problem with coffee, that's a problem with very hot water. The flavour is irrelevant. The same thing would happen if you were dumb enough to drink overheated soda, but nobody claims that's an argument against soda. Why should it be one against coffee?