"... thus only holds value because ... our collective agreement that it does hold value."
What exactly do you think the value of a given collection of bits is?
What exactly do you think the value of a given collection of bits is?
The value of USD is not what you and I agree the value is, it's what the government tells us what the value should be. This is not a one to one relationship.
One is based on a transparent mathematical equation between you and I and the other is based on 7 non-elected and appointed board of governors between you and I. That's the difference.
You have no more control over the market price of Bitcoin than you do the forex pricing for USD.