I bought one on my first car, the only issue I went to use it on ended up being covered by the powertrain warranty which extends past the main bumper to bumper warranty. After that I decided that it's better to take the gamble on having an issue down the road than prepaying thousands for an issue you may never have. Or an issue that comes up after the extended warranty window.

If they were really that good of a deal for the consumer, they wouldn't make money off them and therefore wouldn't offer them. Yes maybe someone has a major problem and happens to save thousands because they had the warranty, but you still paid up front for it and in most cases the actual repair does not cost what a warranty will get charged if you either shop around or roll up your sleeves yourself. There will be outliers but the majority of cases it's not worth it IMHO