Everyone needs a periodic reminder to keep their ego in check. On the one hand it drives ambition, spurs achievement, and encourages personal development. There is almost unlimited power in the concept of self.
Me against the world. My achievements.
I think this attitude is very prevalent in programming and the tech world in general. It is manifested and reinforced by the wild popularity of startups (My idea is good and I can go it alone) and the tech visionaries (Gates, Jobs, Musk) who seem to carry the weight of the world on their shoulders.
On the other, overfeeding your ego will make you narcissistic, selfish, insecure, and hostile. You will lose your empathy for others, and ultimately, your humanity, as you start to lose sight of the big picture: progress is a process that started long before your time and that will continue unimpeded to infinity, even after your infinitesimally tiny ego is wiped from existence.
As Isaac Newston put it best: "If I have seen further it is by standing on the shoulders of giants."