As a 52-year-old electronics geek, I've bought more pieces of gear in my life than I can remember. The failure rate during the warranty period -- or even the extended warranty period, had I chosen to buy extended warranties -- has been vanishingly low for me. In 1989, I had a motherboard on a PC go bad. It was still under warranty, so they replaced it. Some time during the 1980s, I had a CD player fail during the extended warranty period. It was one of the few times I purchased an extended warranty; unfortunately, the store I bought it from had gone out of business. I got AppleCare for my 2008 MBP, and did use it to replace a battery that wouldn't hold a charge. The battery would have cost $80 had I not gotten my $200 AppleCare (at a student discount). I bought extended warranties in 2004 for my big Mitsubishi HDTV and expensive Yamaha receiver, when told what repair costs typically would be. Both pieces of equipment are still going strong. Other than that, I've avoided extended warranties.
In other words, had I gotten AppleCare for all of my many pieces of Apple gear, and extended warranties for all my other electronic equipment, I would have shelled out many thousands of dollars over the years. Based on the extremely high reliability rate of the gear I've owned, it makes financial sense to me to forego AppleCare and take the risk that someday I might have to replace an expensive item that otherwise would have been covered. I don't think it's valid to compare AppleCare to auto insurance or health insurance, where not having it can wipe you out financially. Having a MBP die between the first and third years would sting, but spending $1,500 on a new one wouldn't send my house into foreclosure.
For people who get peace of mind from AppleCare, that's perfectly fine -- it's part of the value equation. But in the long run, if you buy a lot of gear, I think you end up losing money.