Do you ever ask your parents things that you know isn't your business but really want to know anyways?

I would assume that she is like millions of other parents in the world who did the best to provide for their families and buy a house, car and basic parenting/living costs which ended in debt and not much to show. Once you realize the full cost of raising a child including shelter, vehicle, clothing, food, activities, birthdays, etc you will find its pretty convenient to use that little card for all these things and watch it build up to an unaffordable price with interest so high you no longer see a point in even trying. It happens. I would leave it alone.