For a while now I've been collecting nickels (stuivers, 5 eurocent coins) in the hope they will become scarce and will increase in value
The thing with money is they basically have two kinds of value systems
1. The value that is written on it. That's the value a nation has given to it
2. The product value. Just like bread the nickel can become scarce or plenty, which changes the product value of that kind of product