(Mortgage interest rates went up greatly between 1975 and 1980, but setting that aside...) These days it's hard to imagine not borrowing as much as possible be

(Mortgage interest rates went up greatly between 1975 and 1980, but setting that aside...) These days it's hard to imagine not borrowing as much as possible because prices are so high and rates are below inflation. But back then why wouldn't someone, say, live with their parents until they can buy that $50,000 house in Palo Alto entirely from their savings? No doubt that seemed like a lot of money back then. But regardless, at some point, interest rates get high enough and principal low enough that you might actually choose not to borrow money.