A lot of income inequality is hereditary: wealthy parents can offer their children better education, connections, support and other resources that help to advance their prospects in life. Hence, these children will also be comparatively wealthy, on average. An initially unequal wealth distribution results in a self-perpetuating and perhaps even self-enhancing cycle of income inequality. It’s therefore unlikely that a socially mobile and meritocratic society arises automatically.
One of those “other resources” is self-confidence. Very confident people tend to earn more. In other words, levels of self-confidence are correlated with socioeconomic status:
University students are … poor at estimating their own test-performance and over-estimate their predicted test score. However, females, white and working class students have less inflated view of themselves. (source)
And self-confidence, like education opportunities and networking, is passed from generation to generation – not necessarily in a genetic sense. Self-confidence is, therefore, one reason - together with other parental resources – why income inequality survives the passing of generations.
What is more, there is a feedback mechanism at work between two hereditary resources, self-confidence and education: self-confidence has a beneficial effect on education. A positive self-perception has a positive impact on the expected probability of educational success:
Even small differences in initial confidence can result in diverging patterns of human capital accumulation between otherwise identical individuals. As long as initial differences in the level of self-confidence are correlated with the socioeconomic background (as a large body of empirical evidence suggests [see also above]), self-confidence turns out to be a channel through which education and earnings inequalities are transmitted across generations. (source)
Self-confidence can even improve human capital if it’s baseless, as it often is; if, in other words, it’s not grounded in superior personal qualities:
Say you have two people of equal cognitive skills, but one is over-confident about his ability and the other under-confident. The over-confident one is more likely to stick with a subject during the early steep phase of the learning curve – believing that “I can master this if only I apply myself” – whereas his under-confident colleague is likely to give up, thinking the material too difficult for him. Alternatively, the over-confident student might choose “difficult” academic subjects at high school, which qualify him for entry to some elite universities, whilst the less confident one would choose less academic subjects which disqualify him. (source)
And self-confidence does not just perpetuate income inequality when it reinforces the education opportunities of those who already have better education opportunities given to them by their parents. Self-confidence is helpful in the labor market as well, and the labor market is, like education, an area in which parental resources tend to skew opportunities (wealthy parents are better connected to possible employers, for example):
Overconfident people might select into occupations where there’s a high pay-off to the lowish probability of success, such as management, law journalism or politics. Less confident folk, under-estimating their chances, might prefer occupations which yield less skewed rewards. People misperceive overconfidence as actual ability. The overconfident job candidate is thus more likely to get the job than the more rational one. Posh white blokes can – perhaps unwittingly – manipulate the social awkwardness of others for their own advantage, and thus progress at work. (source)