Even if we assume that there is some kind of property-value-to-life exchange rate (that's not a given), by killing someone you are taking, potentially, decades of their life in exchange for the loss of your two weeks.

If you kill someone who has 30 years of their life remaining to avenge your lost two weeks, you are extracting a 780-fold punishment on them. Unless a geriatric steals your Ferrari, the numbers will be similarly lopsided in other examples.