Earlier quoted context omitted.
The 1% contribution to others is good for the manager, because he gets to take credit for the entire team. The 10% self improvement is good for that individual, because he can leverage that into a better paying role.
It depends on where you are in your career. If you are a below average developer, do like they say in the airplane and "put on your own mask before assisting others." If you are an above average developer, you will be noticed by being the person who helps others more than solving every problem. At some point in your career, your influence by your own two hands reaches a plateau. You are a senior engineer. How are the…
My advise to myself 20yo would be: learn how to deal with people, learn how organizations work, build capital and get onto the money side of things; but don't let your ego get tricked into the shiny tech lead and manager titles as those are only mirages of wealth.