Here are two places where there seems to be at least some evidence, one from a conservative blog back in 2011, before it became politically incorrect to question Trump's much-vaunted (and MSM-created) reputation as a great businessman, and a more recent piece from Fortune Magazine. Of course both are spun, but we are all intelligent enough to decipher spin; in any case, one takes the above sources with eyes open.
But for first-hand observation, I see ample evidence of ego clouding Trump's judgment in this six-minute raw video, particularly at 3.30 into the interview, when Trump is asked a wildly stupid and insulting question, "Have you ever asked God for forgiveness?"
A righteous candidate, IMO, would have looked at the interviewer in disbelief, said, "Of course!" and then requested that the interviewer ask a question that was actually intelligent and useful.
When Donald Trump is asked, "Have you ever asked God for forgiveness?" he hums and haws a bit, then answers (to audience laughter, because "confident" arrogance is Trump's schtick) --
"That's a tough question." Then he spends the next several minutes in long-winded fashion to basically answer the question with "Not me!"
That in itself is an example of ego clouding judgment. I'm supposed to be impressed with Trump's honesty by not saying "yes, next question, please?" That's like being expected to be impressed with a guy who admits that he still thinks he was justified in beating up a woman, he's just being honest!