A room is $1k. Over 5 years that’s about $90k at a 7% annual return compounding monthly. So that’s the opportunity cost. But over that period that’s about $750k

A room is $1k. Over 5 years that’s about $90k at a 7% annual return compounding monthly. So that’s the opportunity cost. But over that period that’s about $750k in post tax income which if you applied same compounding is 1.1 m. So that puts you at about 9%. Significant and reasonable if your car is already paid off, I suppose, since you won’t get that much for selling it.