Nitpick, growing into a point:
Zero-interest loans (including, in the very short term, credit cards) are free money. For example, I got my Lasik at 18-months-no-interest financing. I could easily have paid cash up front, but instead, I’ll make the minimum payments for sixteen or seventeen of those months, collecting interest all the while, and then pay off the balance at the last opportunity to do it before interest kicks in. End effect: I get about $200 in interest that I wouldn’t have beforehand. I could play a little hardball and probably make it $300 or even $400 if I got lucky (with the caveat that it could be $100 if I were unlucky or I could come out behind if I were stupid). Even if something happened to my financial situation, I could blow away the loan at any time without repurcussions. Free money.
Similarly, I try to front-load big purchases to the beginning of my credit card cycle. I don’t spend what I don’t have, but my credit card gives me a month before the bill cycles again, plust two weeks after that to pay it off, so I can accumulate about six weeks of interest, absolutely free. My spending is spread out over the month, but given the frontloading, I’d say it’s an extra $4-5 a month versus what I’d have, spending cash or using a debit card. Again, it’s free money. It’s not much, but why not take the leverage when you can?
This is actually a pretty good example of the problem: money is actually a very abstract thing. Money is a fiction, and it attracts gross oversimplifications. Credit cards are free money. Credit cards are not free money. Both of these are lies. Stocks are ownership of a company? That too is a fiction, but it is a useful one. For any worthwhile company, they cost far more than the fractional worth of the actual company. What stocks really are is part ownership of the company’s (also totally fictional) future earnings, which is a subtly different animal. That’s why Microsoft has been flat since 2001, even though the company has grown and continues to make lots of money - the projection of future growth has become considerably less optimistic; that’s all. Money works in such an incredibly complicated way that anything you could teach meaningfully in a high school semester would have to be stripped down to uselessness, like the arbitrary, regimented “budget” that Antigen mentioned.
It’s not always a matter of family background (My parents think like msmith537 and I’m a public school brat), but as Millit suggests, it really is about your attitude. If you think of money as a way of getting the things you want right now, then you get stuck paying off your credit cards forever, because the credit cards really are money right now (to make things worse, most high-school classes I’ve seen approach it this way and forget to mention the consequences). If you think of money as an expression of your constraints, and you live within them, then you get your basic financially-responsible adult. If you start thinking about money as a tool, as leverage and potential, then your finances become this mercenary game, and… hey, free money.
(Thank you Professor Burgstone!)