Robin Sharma sure does know what he is saying, just like the one above. Being a master or an expert at many is sort of like being inefficient in your deployment of resources, in this case your time and energy. It sure sounds cool to know it all but really, what is the point? Especially when you can easily do collaboration with other people who possesses the required set of skills. Mastering the things that you are passionate or have an interest in will be a more rewarding experience than trying to go at it all. At best, you will only be able to dabble just dabble in the larger pool instead of focusing on just a few. Remember, achieving mastery is not a short process. Besides time, it requires an insurmountable amount of dedication in order to reach the master status. Plus, it is much easier to remember someone for something really good than many, but just average.