[rtpg]

The pedantic response:

- if 1 BTC were $100 trillion, then it's clearly passed the fundamentals of "being a unit of exchange between commercial entities", since it would be way more than what any form of exchange would ever require.

The truth behind the pedantic answer:

- if it's a store of value, then the "fundamental" value is the amount of fiat that's gone into the system so far. If all the exchanges have roughly $100 in USD deposits, the base value of their bitcoin deposits will be at least $100, roughly.

- If it's as a means of transactions, then the fundamentals are linked to how much transaction volume is going on. For example the flow of USD into BTC and vice-versa. BTC <-> BTC exchanges in that universe probably help to define things as well, as it would be used as an alternative to USD.

The dollars don't come from nowhere, so there's at least some base numbers you can think about. Thinking of it as "USD going into the ecosystem" and "USD going out" is a good proxy for now I think. Obviously very fluid, though.