Bitcoin cant replace money. Money is supposed to be spent and not hoarded. Thats why inflation is needed so people go spend their money and create jobs and wealth for society as a whole.
Why do people believe this? Where did you first hear it?
This is my personal opinion Everyone gets upset about inflation, its like this bad word.
Money itself is a means of exchange, a substitute for trading actual goods and services. It doesnt need inherent value, it only needs to be accepted by society.
If the growth of money is limited and money over time increased value people are less inclined to spend it. If its going to be 3% worth less next year people will go out and spend it for example for gold.
Now the money beeing controlled and monopolized by a central authority is an entirely different problem.
Check out The Wörgl Experiment for evidence how money circulation creates wealth and not money hoarding/saving. You can save in real estate and commodities but not in money. You can trade in commodities like gold but theyre not good money for society as a whole.
If you can easily swap your spending money for saving money, why would you bother and not simply spend the saving money? The only way to stop people from doing this is to make it very difficult to use the saving money, which, as you mention, is the core point of central banking for further nefarious purposes. Even if there existed an infinitely inflating cryptocurrency, for example, what would the benefit be to the individual?--naturally, he wants his savings to be savings.
How do you convince people to use the money which does not retain its value? Aside from coercion of course
