What should I learn in computer science?

There are loads of technologies to learn in computer science.

So first of all, you must select your ‘area of interest' in computer science field. Your interest matters the most while developing the career rather than scope or demand. If you are working in the technology of your interest then you can change the world. But you are working in the technology which is more demanding, but if you do not have interest in that technology then your life may become bored.

So instead of asking “what should I learn”, it will be better if you ask yourself “how should I learn to develop my career?” Will be the better question.