Money is an IOU. Bitcoin is an IOU but the ledger is decentralized rather than in control of banks.
Once you start seeing the value of any currency as one of itself rather than trying to express it in a different value system, a Bitcoin needs nothing but its inherent worth as payment.
That said, because we all still use traditional forms of currency, a Bitcoin is now worth, say, 112000 breads. It’s worth two new mid-sized cars.
Value is based on scarcity and demand. If something is hard to come by, like bitcoin currently is, the price is hardly affected. But if demand is higher than the supply, prices skyrocket. Demand dies down the moment people feel like crypto is a scam. Supply will stop since Bitcoin has a physical limit (of the top of my head 21 billion). It is no longer realistic to start mining the stuff and receiving it for payment is just silly at this point.
But to flip it around, what is the value of a US dollar, without expressing it in terms of another currency? It used to be tied to gold. You can’t really state one dollar is equal to, say, one bread. The price of bread has fluctuated. Or, has the value of a dollar fluctuated and has a bread always been worth one pair of socks?
Baseline: everything is worth one of itself and trying to express it in another value system is just a snapshot, a moment in time which will have changed soon after.
If you haven’t yet, I can really recommend reading Satoshi’s whitepaper on what Bitcoin is really for. The fact that crypto is now used as an asset to trade in order to gain ‘old’ money really spits in the face of the ideology of a decentralized ledger. And the fact that a dollar value is assigned to it means it becomes the target of a lot of scams. The fact that a decentralized ledger also means greater anonymity has made it a popular target for illicit activity as well.
But by design, it really only wants to take power away from banks in order to stop devaluation, make it impossible to charge people for transactions and to put control of assets into the hands of individuals. The amount of money currently in circulation is way more than the actual physical amount available, because banks can lend you money they don’t even have. Bitcoin would make this impossible.