The cost of fiat money is backed by the belief of people that they can exchange it for something valuable. And only people's belief in "green papers" determines their value against the "orange papers".
Therefore, after understanding this fact, we can make a simple conclusion - any equivalent in the form of paper, metal coins or electronic records only has value, when the established systems of control created the belief in the minds of every person that the sheets of paper painted in a special way have a magical property of converting into goods or services.