Numismatists. Ever hear of them? They're followers of a hobby commonly referred to as coin collecting. Collecting coins is a large following for a few reasons, One being that it can be done for fun, profit, and is good at making memories.
Coin collecting has become a popular pastime for many people, and for every aspiring hobbyist there is a person who collects coins as a business. There is a story of a couple who bought a bunch of coins when their daughter was born, and stuffed the coins in a cigar box. Years later they gave it to the girl as a wedding present. To everyones surprise, the coins' value had gone from a few dollars to thousands!
There is another story of a man who found a coin on the bottom of his closet and found it interesting. He eventually learned that the coin was a rare one-in-three illegally printed coin that was worth upwords to one million dollars! As you can see, this isn't just a hobby, it's an investment.