In my work I meet a lot of people who deeply undervalue their capabilities and by extension themselves. While some of it is an innate lack of self-esteem—yes, nature does play a part—much of it comes from their job title. Picture this if you will.
You are at a BBQ and meet someone new. One of the first things they ask is "What do you do?" The purpose of the question is in part to understand, but it is also to judge—your respective places in the social pecking order. Say you are a junior manager for a small company and you might get a derogatory "You'll never own a boat doing that!"—yes, I have been to some BBQs with real prats. Conversely, say you are the CEO of an ASX listed company and watch people straighten their posture a little. Unless of course your company has been in the papers for all the wrong reasons, and watch people goggle in disbelief.
"What do you do?", like most things at BBQs, is a proxy. Just as a sausage is a proxy for meat, if you don't believe me check the contents of the average sausage, job titles are a proxy for success. They are also, more often than not, utterly useless in conveying an individuals capabilities, much less their potential, much less still the likelihood they will be a sparkling conversationalist.
This is because titles perform two sleights of hand. First, they project status that may bear little empirical relation to competence, thereby misleading colleagues and stakeholders. Second, they seduce their holders into career foreclosure: If my business card says 'Chief', surely I have arrived.