Ego would be making sure you got "your" sprint tickets done, did no code reviews, skipped the retro. I think few people do that but they will if Goodhart's Law happens.
It's a tricky business, being a human being, with its very many pitfalls.
For practical purposes, if you don't acknowledge how good and bad behaviors can both spring from the same base emotions/thought processes then it's harder to grow out of the bad behaviors. You need to be able to reframe how the ego interacts with your work, not just try to kill it off.
Thus, it's never a balanced setup where everyone's happily working towards a shared vision in equilibrium.
There's always someone having a larger incentive than the other person, overriding their decisions in a haste, in order to reach a bonus objective.
Welcome to the real World driven by capitalism.