Success not meaning doing work that makes a difference, helping others, achieving contentment, or having a balanced meaningful life.
Not that the stated qualities don't help you with accomplishing the seocnd as being able to communicate appropriately is a powerful tool, but I've found the person on my engineering team that does the most actual work right now is the quiet guy who isn't trying to lead the team, doesn't spend a lot of time talking in meetings, and just diligently chips away at whatever he has been assigned. His quality of work is high, his output consistent and his stress and complaining seem lower.
Meanwhile as a loud "senior engineer" I have to spend all day trapped in meetings and arguing with people and get to spend very little time doing what I enjoy, spending more of my time fighting the "process".
I am more "successful" but I wish I was him.