If we have to choose between two products that look similar at first glance, we usually choose a cheaper product. Why is this happening? The rule is simple, why should we overpay, since the first product, in our opinion, is as much worth as the more expensive product.
Unfortunately, the devil is in the details and usually the cheaper product is of lower quality than the more expensive product, but you cannot see it immediately. Therefore, people choose what is cheaper, and the manufacturer of a more expensive product must leave the price to make his product competitive, which entails a decrease in quality. Then history repeats itself and worse displaces the better.

The same principle also applies to money. At the beginning, when the money was still functioning as pure gold coins, someone came up with the idea to add some foreign metals to the gold so that people do not realize. The idea passed because at first glance there was no difference. After some time, it turned out that there was more money in the money than pure gold. All because the average person cannot tell the difference between a better product and a worse one if the differences are small. Once you get used to the new product, you can once again lower the quality of the product so that it does not notice the difference. After all, the difference is so big between the final product and the original one that you can't miss it. It is usually too late then for various reasons to go back to the original version.

That is why central banks can print money, thus destroying the currency, because the more it is on the market, the less it is worth. After some time, only hyperinflation will occur but hardly anyone cares, then the old fiat currency will be abandoned in favor of the new one, which has happened more than once in history. Mostly ordinary citizens unaware of the whole operation will lose out.