First of all, the OP says "probably", not "always". It sure does not apply to everyone, the claim is it's just a likelihood. Secondly, you can say that career

First of all, the OP says "probably", not "always". It sure does not apply to everyone, the claim is it's just a likelihood. Secondly, you can say that career selection in your 20's impact your later earnings, even if the actual growth of earnings happens later. An indicative example is of course two persons, citizens A and B. Citizen A goes to work in manual labor after primary education. Citizen B goes to high school and then gets a university education. Citizen A may well be earning much more in his early 20's than citizen B. Depending on how long the studies take, citizen B has earned little money by the time he/she is 25, while citizen A who went straight to work, say in construction, has been accumulating earnings for many years. Still, the future potential of earnings for citizen B has been built with the education, even if it is not visible in his/her annual earnings yet, and the only monetary thing to his name is some debt taken for studies.