If you have everything in bitcoin then you have to spend as well as save. If you don't have everything in bitcoin and spend in dollars that is still an opportunity lost because you could have bought sats with the money. So, whether you pay in sats or dollars you still have the same loss in growth potential as bitcoin increases in vaue. It's unavoidable. Yes there are cap gains tax but that just means you made money. Also if you are sitting on a potential loss because the price is down then spend the fiat. It's a dance.