The value of Bitcoin also depends on your ability to convert it to real world money, since contracts are denoted in real world money.

I'd argue the real value of money lies in contract enforcement. And I am talking about real world physical enforcement like police throwing you in jail. In financial engineering literature we don't really care about the real value of money, the only assumption needed is that contracts are enforced. If that is the case then you can hedge.

For example: You sign an employment contract where you get paid in USD. You also sign a rental and utility contracts in USD. If salary > housing cost, then you essentially have your housing needs hedged. You don't really care that USD has "real value". The value of USD lies in the fact that these contracts are enforced by the government.

The rarity of a currency is important in the sense that contracts don't make sense for all parties if the currency is too abundant. For example, if you can find USD laying on the street, then you would not work for USD. The rarity mechanism itself is not important.