I, myself, never took Don Rickles as a hateful person but always attributed it to being his act and his nitch. He came up in a time when had he been like Kathy Griffin he would have been drummed out of the industry. I could be wrong but I just never thought of him as a hateful or hate filled person.
http://www.cnn.com/2017/04/06/...-jillette/index.html
http://www.esquire.com/enterta...t-art-of-the-insult/
The time he lived in was different and so was society and what was acceptable.