When I was young, I used to collect and trade baseball cards with the other kids in the neighborhood. The cards we collected were not really worth much money, so whenever I tried to trade for a card, I was always pursuing one of two objectives: collecting cards from my favorite player or team, or completing a series.
As an adult, I still find myself collecting things, although I have moved on from baseball cards. Now I collect technology, and if I had to guess, you probably do too.