When a person earns a dollar and does something with it other than spending it immediately (deposits it in his bank, hides it under his mattress, or simply leaves it in his wallet), he has a right to expect that a day later or a year later, that dollar will still be worth a dollar.
Technically and legally, governments are supposed to have the exclusive right to coin money: but when governments abuse that privilege, they run the risk of losing it. That is entirely similar to every other situation in life in which a privilege is abused. Governments abuse this privilege of having exclusive rights to coin money when they do things that are highly inflationary, particularly when they create money to buy votes or when they mess a nation's economy up so badly that all anybody can think of to do is mail out Bernanke-style helicvopter money in the form of checks to the general populace, which is the situation the United States is in now.
When governments engage in those kinds of activities they should anticipate that people will look for and find other mediums of Exchange. The el Salvadorans have at least grasped the general idea in the picture.
https://youtu.be/sLFMmecA1H4