You will find lots of people benefiting from their extended warranty.
As I noted in my previous post, Mercedes spent ~$12,000 on warranty work on my car during the extended warranty period. Also, it was not "optional" work that I would not have done had the car not been in warranty. They were repairs required to keep the car safe and on the road. Now, that was retail, but MB (then anyway) paid the dealers full retail for warranty work. That is a huge benefit to customers, as the dealers never quibble over warranty work.
My car was a bit of an oddball, in that the warranty pricing was low thanks to the previous years being quite simple cars, but my particular year had a bunch of new, expensive technology that was not very reliable, chiefly they 722.6 five speed automatic. That alone accounted for $8K of the bill.
We strongly considered an extended warranty when we bought the Corolla, but even though we drive cars for 300K or more, the initial cost was too high considering the reliability of the model and our ability to self insure. In the case of the Mercedes, I was still reeling from spending $30K on repairs and service over 2.5 years on certain other German brand car, and knowing about many of the new parts in the 98 C-Class, opted for an extended warranty.
Extended warranties are not inherently good or bad, and are available as a tool to manage risk. Whether you buy or not has nothing to do with your savvy as a consumer, but simply your ability/desire to be exposed to risk.