There are different forms of rudeness it's wise to be aware of.
Sometimes people are rude in order to attack, punish, and diminish for their own purposes.
Sometimes people are rude because they're shooting past formalities and going straight for the source of the problem: the ego, nestled and protected.
I once said to Joe, 'Do you support me?' (I was being a little shit), and he replied, 'I support you but not your character defects.'