TLDR: When you buy a hail-damaged car, you
get a discount. When you sell a hail damaged car you
give a discount. The discount you give is always lower than the discount you get, hence you come out ahead in dollar values.
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I get all that (and will address specific comments below), but first, look at it this way:
1. The selling price of the car without hail damage at 3 years old is `$X`.
2. The selling price of the car with hail damage at 3 years old is `$X - $Y`, where `-$Y` is the value of the hail damage (hence it is negative).
3. The selling price of the car with hail damage at 9 years old is `$X - $Y - $Z`, where `-$Z` is the value of the depreciation (also why it is negative).
Since the car selling price never gets to zero or below AND $Z flattens out over time, $Y must also flatten out over time! IOW it is also asymptotic.
This means that the discount of buying a hail-damaged car (the `-$Y`) is large for a new car and small for an old car.
In practical terms, in the context of buying, using and then selling a hail-damaged car:
1. You buy a $30k car and get a discount of (say) $10k due to hail damage.
2. Six years and many miles later that car, which might have sold for $10k without hail damage, will now sell for only $7k.
You got a discount of $10k and only gave a discount of $3k. You're $7k up.
> If I buy something that is normally worth X, but it is damaged and is now worth 0.3X and there I pay 0.3X I did not save 0.7X off what I got... I got something worth what I paid.
You are conflating `value in market` and `value of utility`. Whatever you are paying for a product, you pay that only because the value you get from the that product is greater than the amount of money you are paying.
Hail damage does not reduce the utility value of a car by even a single cent. It will transport your cargo and passengers exactly the same and with exactly the same levels of safety, comfort and reliability that its non-hail-damaged counterpart would.
The utility of a hail-damaged car is exactly the same as the utility of its undamaged counterpart. The difference in price between a hail damaged car and its undamaged counterpart is the exact monetary value placed by the market on "how pretty is it?"