In my opinion, they are thinking like that because they dont have the knowledge about our modern technologies today, most of the people who are criticizing cryptocurrency are those people who are old enough that they cannot understand how to operate a simple ipad, so they literally dont have a clue about the way our system is going.
They are not just the paper but paper with a legal tender and the word of the government that it is the responsibility of the government to let you have anything legal commodity with the paper money provided the value of commodity matches what you are willing to pay.
So this is what the government promises and of course has such a great amount of advantages that it carry out and meet the needs of everyone who hold it.