Currency is not given value because people "believe" in it or not.
It has value because the government decided that to operate inside its country, you must use this currency. This is enforced through taxation. It doesn't matter if you believe in the dollar or not, at the end of the day the government will tax you for a dollar amount and you're gonna have to pay in order to keep having access to the US market.
This is why cryptocurrencies have no inherent value, only value as it pertains to actual currencies.
You can have multiple currencies in use at the same time. A good example would be the Soviet Union where vodka could buy you things that rubles couldn't. Or as a more current example there's Venezuela, where the government backed currency is the Bolivar but most transactions happen in USD or Columbian Peso.
Yeah that's true, that happens when trust in the government has been lost, or when trying to avoid taxes. But there's an important distinction there. People use alternative currencies when the government is incapable of punishing them for doing so, and when the local currency is inconvenient to use, such as during hyper inflation. It has nothing to do with whether they believe it has value or not.
You make two strong arguments about why the value of money is based on people's belief in it's value. And then you just ignore them.
As you said, if people don't believe the government will enforce it, it has less value. As you clearly say, it doesn't matter what the government says, it matters what people believe.
And it hyper inflation or matters what people believe future value is.
You should rethink your definition of money because you've essentially demonstrated its value derives from belief.
It has value because the government decided that to operate inside its country, you must use this currency. This is enforced through taxation. It doesn't matter if you believe in the dollar or not, at the end of the day the government will tax you for a dollar amount and you're gonna have to pay in order to keep having access to the US market.
This is why cryptocurrencies have no inherent value, only value as it pertains to actual currencies.