Obama himself said something along the lines of “Let’s face it. Anyone running for this job is not exactly normal to begin with.”
I absolutely believe that Obama had been trying to live up to his dad’s image until he finally went to Africa and learned enough about his Dad to realize that Dad hadn’t been all that. And even then, he still had that internalized image to live up to.
We all have an image developed in early childhood that we try to live up to. It’s just that for most of us, the standard is set a bit lower. In McCain’s situation, knowing that Dad and Granddad were admirals (and disappointed and angry admirals at that) didn’t leave all that much maneuvering room above it. In Obama’s case, Dad was Mythic Being, loosely based on family legend and built on by the dreams of an imaginative and well-read boy. Add to both a strong sense of duty, a good helping of ego and a big dose of ambition, and I think you’ve got yourself a presidential candidate.
Except that there are surely lots of eligible people who share those attributes who don’t run for president. Even so, at least you’ve identified four factors, which is more than the OP’s laughably simplistic “McCain’s reason for running - Inferiority Complex.” with “He is also running because he feels entitled” almost as a footnote.
Yes, because most people with those four attributes don’t measure up, or the downside is too great. The cost is enormous, and very few people have enough public profile to even consider it anyway - maybe a thousand at most in the entire country. So now you start narrowing it down quite a bit.