One quibble: since bitcoin is almost perfectly durable, it is relevant what it could have bought later because saving it was an option. That's the major friction in getting people to spend their bitcoin.

How does the tendency towards higher productivity factor in to your argument about this dinner being similarly affordable as it was over 50 years ago? Shouldn't everything be getting more affordable?

I think part of what's going on, that does relate to inflation, is that there's another side to the Cantillon story that often gets overlooked. Rich people and poor people buy different things. If rich people benefit from getting the new money first, the things they buy will also tend to increase in price first, which will make them relatively less accessible to poor people.