> As time passes there is more fiat in circulation, which means fiat is worth less

This isn’t always true. For one thing, the amount of fiat in ‘circulation’ isn’t just a matter of “count up all the bills printed”, but is affected by how much leverage exists in the world and many other things.

Second, even how much a fiat dollar is worth is also a factor of how much productivity there is in the world. To understand what I mean, let’s imagine a super simple economy with only fiat dollars and wheat. Every dollar is only used to buy wheat.

Say there is $1000 in bills and 1000 pounds of wheat. Each dollar is worth 1 pound of wheat. Then, we print an extra $1000 in bills; that would be inflation, and now you can only buy 1/2 pound of wheat for a dollar. That is what people imagine when we talk about printing more money causes inflation.

But what if new technology gains means we are able to produce 4000 pounds of wheat for the same amount of work; now, each $1 can buy 2 pounds of wheat. Even though we printed more money, the economy grew even faster than we printed extra money, so we didn’t get inflation and instead prices went down.

Inflation is always (generally) about the ratio between currency production and economic output growth. You can’t just look at one side of the equation.