There is always so much to learn. It may be in your own field, there is always something that gets updated. But, especially when it comes to tech, there is a rapid change.
I am experiencing this. No matter how much you learn, you will definitely miss out on something. Even the basic stuff gets misplaced in your head if you are not using it for a long period of time. So nobody can be a complete expert. It’s all about the experiences that you have which matters for you as an individual.