[rainsford]

A significant difference in lifetime earnings doesn't necessarily imply a large jump in early career earnings. For example the difference in lifetime earnings could come entirely from significantly higher income later in a career that more than makes up for a lower starting salary.

Some professional careers work exactly like this, for example pilot or doctor. Lifetime earnings would be a much better comparison than just looking at the first few years of a career to asses if the educational investment was worth it or not.