You need to make your peace with the fact that there will always be vastly more things you don't know than things that you do. That would be true even if your life were 10x longer or 100x longer. Your life span is not the limiting factor. The size of your brain is the limiting factor. At the very least, there are 8 billion other brains out there, and your brain cannot contain all of the knowledge contained in those 8 billion others.
But there are some fields of knowledge that give you more leverage towards obtaining expertise than others. Being an expert in Lisp, for example, will not make you an expert in C++. But it will let you realize that becoming an expert in C++ is very likely to be a waste of time, because being an expert in C++ means knowing a lot of random and mostly arbitrary trivia that has accumulated over many decades of bad decision-making.
There are a lot of examples of subjects that give you similar kinds of leverage. There are probably a dozen core topics that allow you to cut vast swathes through most of human knowledge: basic physics (GR and QM), the theory of computation and complexity theory, game theory and the theory of evolution (and how these are related) is probably the 80/20 list. So if you really want to maximize your expertise I would start by focusing on a few of those topics.
But, as others have pointed out, you really should take a step back and ask yourself why you want to become an expert in many things. Do you want expertise for its own sake, or do you want the prestige that comes from having others perceive you as an expert? Because those are two very different goals.
But there are some fields of knowledge that give you more leverage towards obtaining expertise than others. Being an expert in Lisp, for example, will not make you an expert in C++. But it will let you realize that becoming an expert in C++ is very likely to be a waste of time, because being an expert in C++ means knowing a lot of random and mostly arbitrary trivia that has accumulated over many decades of bad decision-making.
There are a lot of examples of subjects that give you similar kinds of leverage. There are probably a dozen core topics that allow you to cut vast swathes through most of human knowledge: basic physics (GR and QM), the theory of computation and complexity theory, game theory and the theory of evolution (and how these are related) is probably the 80/20 list. So if you really want to maximize your expertise I would start by focusing on a few of those topics.
But, as others have pointed out, you really should take a step back and ask yourself why you want to become an expert in many things. Do you want expertise for its own sake, or do you want the prestige that comes from having others perceive you as an expert? Because those are two very different goals.