You also need to consider the role of blind, brainless optimism.

People overestimate their chances of making it to the CEO level in large corporations, unaware of just how much the game is rigged against them, especially if they didn't inherit a network of connections. Since people-- especially the talented young people who are the workhorses of most companies-- tend to make career decisions based on future income, this is a way to inflate peoples' anticipated future income with no intention of delivering on the promise.