I feel nowadays people just buy and HODL and the price keeps on going up only because less and less BTC are available on the market, being HODL by people.
That's the supply and demand effect you just described. The demand rises or stays the same at worse, but the supply keeps decreasing. it's true what you are saying. Not that long ago I read a post somewhere that says that the amount of bitcoin on cryptocurrency exchanges hasn't been this low since the 2017/2018 era. That news came out around bitcoin's recent rise to the $67k mark. Even with a new all-time high, people (especially miners) don't want to sell. That tells you that the community is confident that the price will increase even further.
Most stores that have adopted Bitcoin payments may or may not be the ones that we regularly use in our everyday lives (it's on a person by person basis)...
In addition to that, many merchants use payment processors that immediately swap crypto to fiat for various reasons. So, even if a store accepts crypto, their end-goal is converting the coins to fiat.