[HideousKojima]

>if

That single word is doing all of the heavy lifting for you. "If" the housing market will never crash, then it's a surefire safe investment! Better buy tons of houses to flip on credit. There's no guarantee that your debt/investment will succeed, which is why banks try (and often enough, fail) to price in risk with things like varying interest rates, collateral, etc.

[airstrike]

the 90% accounts for the "if". my point is there an expected value for the future revenue amount, subject to your own assumptions about the probability of each outcome and your discount rate for the value of that money over time

in scenarios where your expected value discounted to present value is greater than the alternative, you make the investment. it's really finance 101... it's just NPV