Dr. Disrespect is a character. He created the character with certain key elements and they worked together. His character is rude which is why dr. disrespect is rude. You can tell by the name that the character was meant to diss people. However, the person himself is nice.
In the rare glimpses when dr. disrespect breaks out of character, you can see that he is a nice and decent person. Just like actors play rude and selfish characters, he plays his own character on stream. It is the beauty of his skills that he is able to convince his audience that his character is his true self rather than just acting.
