The 'blow to our ego' here is the realization that maybe you're not as awesome as you think that you are, and all of the "I could haves" are really lies, because you couldn't have. At least that's my interpretation of that comment.
I don't know. The idea that you had the skill to do something amazing, but not the discipline to follow through seems to imply that you couldn't do it.
For example, say you see discipline and skill as the two ingredients need to do something amazing. It's easy to say "I had the skill, but not the discipline, I could have done it." But is that really any different than saying, "I had the discipline, but not the skill, I could have done it." Discipline is probably just as difficult as the raw development skills to master, yet it's really easy to convince ourselves that it's just a matter of 'doing it.'
Maybe it's more that I could have gained the skill if I'd worked harder. I fully realize that discipline is harder than raw development skills to learn, and that it's the critical ingredient in any major venture. I understand that, but when I have to really work to finish something I tend to fall down. Which is why it makes me feel horrible.
I'm pretty sure I know what you're talking about, and I'm pretty sure that's not what's happening. It's not helping my ego.