I don't consider a little bit of ego to be a bad thing in a pilot, provided it is balance by competence. I agree that it's like "self confidence", which is vital, but to me, a little bit if well mannered ego can assist a pilot in following through on a good plan, as opposed to second guessing themself. Yes, the plan should be good in the first place (not pressing on into poor weather), but if the plan is to conduct a flight within your skills and training, and within the limitations of the aircraft, and weather conditions, a little ego can keep you moving forward with confidence.
Many times, I have been told, "There's the 'plane, go fly it". No type training, 'never flown one before, just go fly. Obviously the person responsible for the 'place is confident that I can handle it, so I should be too. My ego helps me with that. My common sense demands that I read and understand the contents of the Flight Manual, and ask any questions before I fly. But, once I'm flying, my ego reassures me that I can do it.
If faced with a system failure, deteriorating weather, unusual attitude, my ego supplements my self confidence to tell me that I can get through it, and land safely. For all the times that I have been being mentored by a more experienced pilot, each time they have said "you can do it..." they were bolstering my ego, as well as my self confidence. I learned to expect more of myself, which at least means to never expect less!