The company is not paying you for the amount of expertise. It is paying for how much money you will make them. If you limit your work to only what you can do yourself (without leading others), then you have deminishing returns. Only because I can now solve very complex problems because of my expertise, I cannot do 10x the work. Time is limited, expertise won’t bring you more of it. Leading will help other do their work better and faster, so you will be more valuable with that.