If BTC replaces fiat, I don't believe it would increase in buying power at a rapid rate. I think it would gradually increase in buying power over time only because the total supply will gradually shrink due to lost coins / dust /etc.
Imagine what would happen in this imaginary world when GDP increases. More things are being produced which means there are more things that need to be sold. But there is a fixed number of coins to buy things with. Each coin has to be able to buy more things.
> Let’s assume BTC replaces fiat (USD)
If BTC replaces fiat, I don't believe it would increase in buying power at a rapid rate. I think it would gradually increase in buying power over time only because the total supply will gradually shrink due to lost coins / dust /etc.