Its self-inflicted and part of a larger culture of Having More Stuff. Having lived most of my life in South America and later migrated to North America, I feel I can see that more clearly than people who grew up here.
People always go over the top with anything material. Have a single child? You need a minivan. Family of four? You need a 3-level, 2000-sqft house (with the garage where you will never park your minivan, because it is full to the ceiling with clutter you never use). Toys are just another facet of this culture.
As someone from the outside who has been around, I can say the rest of world is not like this. Its not particularly hard to avoid. Just buy less stuff, and donate/dispose of things you don't want or need.