There are all sorts of motives for people to debate . . . but in my estimation, you cannot be insulted or hurt unless you allow it. If your self-esteem is so fragile that you take another person's tongue personally, then you will be at their mercy all through your life.
Everyone has an opinion and everyone wants to be considered influential; unfortunately, there are those who can only do so by bullying, intimidation, and personality assault-- some even physical assault if nothing else will work. Of course, when defamation of character or physical assault happens, that is another matter and proper actions should be taken . . . but in the long-term, pick your battles for battles do not win the war, but the long-term strategy does.