how does money become a unit of account? which happens to be the final hurdle for Bitcoin.
by making it cheap and easy to use (little to no tx's fees) thus allowing it to become widely distributed and accepted. btw, when i say widely, i mean globally b/c this feature is critical to a successful and secure Bitcoin (it absolutely needs to transcend national borders to setup the game theoretic of international "competition" or FOMO). inexpensive tx's makes it ideal for smallish tx's (coffee) and use by even poor people (use by poor people is also critical for security as they have the most to gain by rebelling against the State fiat money). onchain tx's also represent finality, as bitcoin is a bearer instrument. it's a "push" technology that can't and isn't expected to be taken back (reversed). this property doesn't create false expectations btwn parties or time to "second guess" oneself. what's done is done. which is how ordinary ppl learn to trust Bitcoin and then use it on a daily basis for ordinary trade. which is why RBF and it's variants are destructive and irresponsible. irreversibility enforces responsibility and good decision making. which is what sound money is all about. it's also instantaneous w/o opportunity for the participants to change their minds or circumstances to change over time (think smart contracts require time or LN micropayment channels that can be spammed to prevent closure). CSV doesn't fix anything there b/c lots of value will change hands bidirectionally w/o ever having to settle (sounds like fractional teller banking to me). with unit of account money, there are usually no third parties involved either (think LN hubs or lawyers in smart contracting).
Bitcoin will never become a unit of account w/o the above properties.
When you do business on some level of complexity, you need to have a measure of how much value you have created, that is needed to adjust your business. A farmer could count cows, a shipowner could count ships or tonnage. He could meet a friend at a shipowners convention and say: Now I have twenty ships. Dollars are convenient for measuring value, except, you can't really use dollars as a measure of value over any substantial span of time. You have to adjust it by inflation for example, or the dollar index or a combination. The value is the supply of dollars, which is how much less people want to hold, and the demand, which is how much more you want to hold. The creation of new dollars is a key to that, and the inflation expectation, and other speculative reasons. There is no objective measure of value, it changes with the individual's circumstances.
In a turbulent money world, you can not use money for calculation and that function of money should be toned down. Of the other two functions, the store of value is the most essential, and the liquidity, the ease with which you can trade them for something else, supports trade, and money is not really a good store of value without liquidity. Those two functions work together, you can not have one and not the other.
The unit of account function, not so much, I really think it should be abolished. Under stable conditions, it can be used, if it supports the purpose of calculation.
AND: You don't really need to use the same unit for accounting as you use in your daily business payment transactions. You can trade in india for rupees, and still use dollars as a unit of account, which many foreign (to India) companies do. The same with bitcoin. You just need some added calculation.
