If the expected utility calculations don’t convince you, maybe this will:
Neither Circuit City nor Best Buy discloses how much of its bottom line comes from extended warranty sales. But analysts have estimated that at least 50 percent and in some lean years 100 percent of profits at the electronics retailers come from extended warranty sales.
Here is the full story. The paper (but not on-line) edition notes that a desktop computer has a 37% chance of needing a repair in the first three years; if you are going to buy one warranty, maybe that should be it. But you are still best advised to buy insurance only when a) the potential loss is very large, or b) your wife insists.
Gabaix and Laibson have a very good paper on myopia, consumer ignorance, and shrouding.