Given that I know some of these people personally (having been in a YC-funded startup) I can assert that the "if you have not specifically worked on your ego" p

Given that I know some of these people personally (having been in a YC-funded startup) I can assert that the "if you have not specifically worked on your ego" part and the "still very succeptible to arrogance / ego trips" is specifically untrue of at least some of them.