In the other sections of the Personality page, you will find quotes and information regarding Danny's personality. Here is where I put forth some of my theories. There are two aspects I'd like to theorize on:
Theory #1: Danny's darker side and the possibility that he was manic-
Martin Gottfried's book, Nobody's Fool, (and possibly Michael Freedland's book, The Secret Life of Danny Kaye) heavily points toward the darker side of Danny: the depression, moodiness, egotism, and rudeness as witnessed by the people Gottfried supposedly interviewed.
Theory #2: My other theory is that Danny had low self-
Kurt Singer's book, The Danny Kaye Story, has a lot of good quotes and information