Does almost everyone from top tier colleges go to grad school?

My nephew works in the music business. Went to Bowdoin, then worked for one of the big music companies as s talent scout and other roles for several years. Left there to become the business manager for a well known solo singer. Lives a good life now – does not have to live where his employer lives, is able to do a lot of work remotely. He rarely goes on the road with the act anymore. Flexible hours, decent pay, and a job he enjoys and is good at. And he didn’t even go to Harvard – imagine that!