“David Ricardo and Comparative Advantage”
David Ricardo is a historically famous economist. One of his most famous concepts is Comparative Advantage. A brief (invented) summary:
Germany and Italy are looking to trade wine and pasta. Germany is very inefficient in making wine, and decent in making pasta. Italy is the most efficient at making wine, and a bit more efficient than Germany at making pasta. What should they do?
According to Ricardo, Italy should dedicate itself to making wine and let Germany make the pasta. Even though Italy is more efficient at both processes, they will be better off focusing on what they are best at and delegating the manufacturing of the other item to Germany. Germany will also be better off.
This applies to delegating any function really. I may consider myself a first-class investor and a pretty good manager. I will be better off delegating management to a manager, even if they do certain things less efficiently than I do, and focusing on investing. If I decide to do both functions, it will inevitably limit my ability to invest. As a large piece of my time will be consumed by a function I am merely good at, not excellent.
In the long run, through delegation, we will both be better off.