Mike Zarnock is what we would call an ultimate collector. He holds the Guinness World Record for the most Hot Wheels cars in a collection, and even has a Hot Wheels car named after him. There are over 20,000 cars in his collection and he has written eleven books on Hot Wheels.
Hot Wheels car collecting is one of those great collecting categories, because they are small, usually inexpensive, and can be found everywhere. You can always make room for one more car on the shelf, as Mr. Zarnock has shown.