When I was a child I associated Lucky Charms with holidays, and therefore - a certain amount of luxury. My family only ate whole grains and healthy cereal, but at Christmas each of the kids got to pick a "sugar cereal" to eat. So, in my child brain, that meant sugar cereals were fancy, and my friends who casually had them in their cupboards were fancy by association.
I was far from alone in my rose-colored perception of Lucky Charms, it's pretty normal for kids to create their own context for what is fancy or luxurious. And one of the more amusing (but sometimes sad) parts of adulthood is realizing how mundane these items we used to daydream about actually are.