Given the existence of a choice between deflating and a hypothetical alternative of a universally accepted stable risk-free store of value, it would be rational to prefer to receive the latter. It is still however, in my rational interest to prefer the latter to not exist at all. Being one of the large majority of people who aren't the unproductive uber-rich, I prefer that those that have far more dollars than me are more inclined to circulate them, creating far more opportunity for me to grow my share of national wealth (and absolute national wealth) than would exist if dollars were to be spent only when absolutely necessary. The corollary of your argument is that if we frame it the other way round, with StableDollar and other non-depreciating capital holders tending to hold more bargaining power than the general labour supply, they will be able to get away with paying only InflataDollars to the point where the level of StableDollars actually circulating in the economy will tend towards zero asymptotically...
In our actual system the ability to deposit InflataDollars into accounts with fixed risk-free positive returns (backed by expected and potential supplies of InflataDollars), the government keeping inflation low, and the government requiring you to pay tax on 30-40% of your income solely in InflataDollars ensures the demand for InflataDollars will never approach zero. In fact, it's much less likely to reach zero than the demand for Bitcoins, Freicoins or tulip bulbs, none of which anybody is obliged to use in any circumstances (at least not until Bitcoin-denominated debts become widespread and readily enforceable. If I wanted to design a cryptocurrency I'd focus on that aspect)
You are obliged to use bitcoins if you want to put something in the blockchain (and no one will do it without a transaction fee). If you aren't using bitcoins otherwise, there is not presently any reason to put something in the blockchain. That could potentially change.
I'm not sure whether or not that is meaningfully different from "you are obliged to use tulip bulbs if you want to grow. tulips." I am inclined to think that it could be.
In our actual system the ability to deposit InflataDollars into accounts with fixed risk-free positive returns (backed by expected and potential supplies of InflataDollars), the government keeping inflation low, and the government requiring you to pay tax on 30-40% of your income solely in InflataDollars ensures the demand for InflataDollars will never approach zero. In fact, it's much less likely to reach zero than the demand for Bitcoins, Freicoins or tulip bulbs, none of which anybody is obliged to use in any circumstances (at least not until Bitcoin-denominated debts become widespread and readily enforceable. If I wanted to design a cryptocurrency I'd focus on that aspect)