I didn't read it at all as entirely career focused. The author is saying "if you have high ambitions, don't hang around with people who have low ambitions." H

I didn't read it at all as entirely career focused. The author is saying "if you have high ambitions, don't hang around with people who have low ambitions." He's not saying "live in a bubble." This has less to do with the advancement of a career and more with your long term goals. The people you are around the most will be the ones who influence whether you reach your goals. Definitely have friends who are very different from you in terms of career, activities, interests. But don't have friends who want you to go out drinking every night if you have grander aspirations.