>>513731356 (OP)
In 1950, the degree of complexity in most decent-paying fields didn't necessarily require a higher education to enter or be competitive. Things axiomatically move toward greater and greater complexity over time, so people now generally need to study + certify for years as a young adult to be competitive in their given field, which means they're getting married and buying a house far later in life (after age 30).
This isn't the entire story with that pic, but it's a big part of it. You should post stats on the % of <30 adults who are doing a thesis on some shit that most people wouldn't have been able to even comprehend in 1950, before calling them lazy.