Central banks have (without evidence) claimed that deflation is a universally “bad thing” in order to justify inflating the currency every single year (AKA stealing from savers, and transferring wealth to the people who are the earliest recipients of the inflated currency).
Gold would have become the standard around the world if governments had not used coercion to prevent it from becoming so, and instead replacing it with fiat currency (which they can control and benefit from).
If Bitcoin, or another cryptocurrency, replaces fiat, it’s value will be worth several orders of magnitude of what it’s worth today, which is why many people are holding it instead of spending it at the moment.
However, people will not simply “horde” Bitcoin forever in anticipation of its price going up any more than people currently spend every single fiat dollar/euro/yen they have for fear of it going down in value due to inflation.
You may ask, “but why WOULDN’T they hold it instead of spend it if they anticipate the value increasing each year?” The answer is because people HAVE to live in the here and now, they have to pay for things like food, rent, entertainment, cars, fuel, etc. So they can’t get around having to spend some amount of money to live.
But sound money (money with low to no inflation) does cause people to spend LESS money than fiat currency because there’s a much larger opportunity cost.