The key is to leveraging a degree is to major in a profession where labour supply is artificially constrained through the possession of that degree. There is good reason that 49% of the top 1% in the US have post-graduate degrees, while the high school or less group actually outnumber those with bachelor degrees only. It is not because of the education, but because the post-graduate degree bought them quota into a supply management system, so to speak.

The trouble is that these outliers, who are able to realize artificially high incomes due to the artificial labour supply constraints, make it appear that everyone with a degree can do better than without when observed on average. But closer inspection of the data does not continue to back it up. Despite substantial increases in college attainment over the last several decades, incomes have remained stagnant.