BTC is less expensive every year so long as its value is relative to its population of users and also available ways to spend it. In theory its way more valuable now then the retail opportunities of years ago, the nominal price rises inconsistently but generally every few years but its justified by the value of possible usage. I do generally go off the potential coming from a larger userbase being the most obvious easy comparative value vs other global assets.
What you said at first about its value relative to population is important I think because more and more people will want to find places where to store and accumulate value without undergoing the various dangers that bank accounts can bring about in some places in the world, but also in regards to inflationary risks.
The ways to spend it are not the most important value driver for bitcoin because most people won't want to spend it. Volatility would have to decrease a lot and this will only happen when a large share of the population feels they own enough bitcoin. Otherwise volatility will remain quite high and undermine the idea of day to day spending.
Comparative value vs other global assets is against important I think. If someone has income that can be spent on building bitcoin holdings, I don't think they will use bitcoin to spend it. Whether you call it userbase or holderbase, I believe more people want to hold it for years to come if they don't have to sell for a reason.