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by mise_en_place 1470 days ago
> Always think in absolute dollars and not in rates. $1000 is $1000 whether the cost per use is pennies or tens of dollars. Thinking in terms of rates is how people would fall for predatory installment purchases in the old days (you can have a new computer for just $2.5 a day!)

It depends on the opportunity cost. If you can get a house for 3600 a month, and the house appreciates in value in excess of the discount rate, then it's worth it to purchase that house.

2 comments

> It depends on the opportunity cost. If you can get a house for 3600 a month, and the house appreciates in value in excess of the discount rate, then it's worth it to purchase that house.

To add to this, there is also the opportunity cost of buying the more expensive option because the difference is only $1/day. Spending $365/year on the more expensive option is missing out on getting some other item[1] for $365/year.

Like I keep telling people who ask me why I don't pay for $FOO instead of using $BAR (where $FOO is "Windows", or "Office365", or some development tool and $BAR is OpenOffice, Vim/Emacs, git from the cli, Linux, etc).

The answer to any "Well $FOO only costs you $10/m, and if you are a professional using it as part of your profession, then you should be able to afford it" is "I can afford lots of things, doesn't mean I am necessarily going to buy them".

[1] Sticking with the phone example, taking a phone that works out to be cheaper by $365/year means that you could spend the extra money for redundancy (if your phone breaks, simply buy a new one in 30m), you get a drawing tablet (suddenly, whiteboarding during zoom meetings saves 30m - what's your hourly rate?), or you put it into a index tracker or stock or debt, and get a positive return.

> It depends on the opportunity cost. If you can get a house for 3600 a month, and the house appreciates in value in excess of the discount rate, then it's worth it to purchase that house.

In this case, the absolute value analysis yields the same result, so it doesn't really "depend". I'm not saying you will always go wrong thinking in terms of rates. I'm saying you'll never go wrong thinking in terms of absolute values.