1. They print fiat.
2. Every rare good on earth rises in price. Also Bitcoin.
But perhaps the buying-power keeps even exactly the same (cause everything costs more). Buying-power could even shrink while price rises in fiat terms.
3. But then they tax my 'profit', eg 28%
I call that the non-deflated tax scam. To give an exaggerated example, let's suppose that in your country, as happened a couple of years ago, during one year inflation rises 10%. Let's also suppose that someone buys $100K in bitcoin and when the year ends sells it for $105K. The IRS will want to charge you 10% of that $5K of supposed profit when in reality, due to inflation caused by the government, the real purchasing power of the $105K is $94.5K and therefore you have not made any profit.
This, moreover, is taking into account the official inflation data which is manipulated downwards, but well, we have to base it on something.
In general a CPI of 10% is extraordinary and if it is maintained at an average of 3%, you will have made profits instead of losses, what happens is that they will be charging you more than they should according to the real purchasing power.