I agree and disagree. Focus is very important. Constantly working towards trying to be best is paramount. That said, myopia or singularity is not the holy grail either. Often the diversity of people’s interests and curiosity, brings a higher level of insight and perspective to their career. Focus and hard work toward one’s goals is not always mutually exclusive with diversity. I agree that in order to be great you have to make sacrifices and not be distracted, nor should one try to do everything well (it won’t happen), but I also believe that the depth and diversity of people’s experiences and passions can also be a strong tool for learning and ultimate success.