The most illiquid investment on the planet - college

"A college education is the most illiquid investment on the planet. Let's say that you buy a hour or car. A few years into owning the item, you realize that you really can't afford it. In the case of a house, you can sell the item and recoup - in the vast majority of markets throughout history - a large portion of what you put into it. If you can't, you can do a short sale and the lender might forgive the balance on the mortgage. This can harm your credit score but all in all, you'll be okay." Zac Bissonnette in "Debt-Free U".