This is why Wii's attach ratio is so high. Each Wii gets used by several people in the house, and they have Wii parties for friends. So building a bigger game collection benefits a ton of people. Buying a $50 game for 4 people makes more sense than buying a $60 game for yourself.
Interesting to see how at a certain age, people get "too cool" for Nintendo, but then every year more of them come back, and then at a certain age, Nintendo's your only choice.