Frugality is also huge. If you can save 15-25% on products you knew you were going to buy anyway by clipping coupons or buying in bulk or searching for deals, that's far better than making 15-25% in the stock market because there's no risk.
The real estate thing, too, isn't as hard as you think. Multi-unit dwellings can often be purchased at the price of a normal house and rented for 2-3x what a normal house would go for. If you can find a three or four unit building for $100-$150k and live in one of the units while you pay down the equity and fix up the other two to increase they're rental value, then getting $500-$600 per unit becomes very possible. That's $1500-$2400 a month to go towards mortgages, which would easily support two $100-$150k houses.