Of course you don't understand, because you don't need them, you can't understand freedom of expression if you never had anything to say, you can't understand privacy if you never had anything to hide, if you were living in a country like mine, Argentina, you would understand immediately the incredibly useful thing that Bitcoin is.
I have a Swiss bank in my pocket, in a country that steals all your savings every ten years and the central bank destroys you with inflation.
I have an international payment system, I can send and receive money in minutes to whomever I want, without asking permission from anyone, without the government or the bank stealing it from me. From a place where it is sinful to take your money out of the country.
It's the difference between existing or not in the world, and you have no idea how incredible it is to be able to pass an Argentine crisis without your family suffering hunger, no centralized system could give me something similar at such a low cost.