Inflation is a decrease in the value of money itself. If there’s a lot more money around today than there was yesterday, then money is less scarce than it was before. Scarcity is a major contributor to value by the theory of marginal utility:
Suppose you have no first aid kit. Gaining a first aid kit gives you a tremendous amount of value! Now suppose you get a second first aid kit. Still valuable, but not as much as the first.
Now you suppose you have a thousand first aid kits. What are you going to do with all of them? You can’t possibly use them all yourself! So you might as well give them away or try to sell them.
First aid kits have declining marginal utility. Having way more than one gives you very little value relative to the value you gained from the first one. On the other hand, those first aid kits will have much more value for other people who don’t have one yet. Thus it’s better to distribute first aid kits than to hoard them.
Most things work this way. One of the main exceptions is money itself. The more money you have, the more you can do with it! Of course, at large enough levels of wealth, what you can do for yourself personally (buy food, clothes, shelter, entertainment) shows the same diminishing marginal utility: being able to afford a steak dinner every day is one thing, but nobody is going to eat 10,000 steak dinners every day!
On the other hand, the other use of money is to hold power over others, and there’s no limit to that, unfortunately. The biggest problem is the existence of people who actually want that!