apple care is an insurance kind of thing. by default, in the long term customer looses, the bank wins.
Agreed. The maths says it's not worth it.
Taking out AC means you expect to have a problem or problems which would be covered by AC (not loss, theft, drops, spills, etc) AND which costs more to put right than the cost of AC AND which happens at some point after the initial warrenty is up but before the 3 year mark... Highly unlikely in my book.
Problem is, of course, that it is always possible...