Psychology of designers

Who are good designers and how to teach designers to make them better? I believe psychologists provide insights into these questions by identifying the psychological skill-sets that successful designers are commonly required to have. I conjectured that good designers need two psychological skill sets: empathy and creativity. I conducted some experimental studies to test my hypothesis.
Then, a few months ago, I posted this question on the discussion board at Core 77, where issues are discussed among designers with a wide variety of backgrounds and perspectives. I expected that empathy, creativity, and visualization ability might be some key psychological factors for them to survive and succeed in as designers. Interestingly however, they need self-oriented psychological traits/skill-sets such as ego, “thick skin,” and desire for stressful situation, to name a few. I temporarily concluded that designers may need self-confidence more than empathy or creativity.
On a related note, Chihiro Hosoe, my designer friend said that designers are generally super charged and create novel and interesting but useless ideas at first and then they quickly find that no one needs their ideas. He said that when these “ups-and-downs” are repeated, the self confidence of the designers are often damaged.
I think that it is really hard for any designers to completely justify their ideas, designers think they need to be confident. I am not saying that designers are not rational or logical, but design solutions often include some ambiguities that could not be articulated with only words.