Is it possible to know everything? Is it well?

Question

People learn really lots of technologies. They learn things which are impossible to use together. How do you think they can be successful in future or not?
When you become a master of smth, this smth can dissappear.

Answer 1

its good to know a little from everything and master one specific field.

Answer 2

You should pick am expertise. It's better to master something instead of being a jack of all trades.

Answer 3

Why exactly was I downvoted?