If you're relatively careful with your machines, it's insurance, and like all insurance, the one who offers it makes $$.
I've had a dozen Mac laptops going back to 2008 (+ a Powerbook Duo in the mid 90s). Only had AppleCare on a couple company purchased ones. Had only one case ($700 logic board repair - ex-gf spilled wine on it) where AppleCare would have absolutely paid for itself, the rest... would come out behind. Amortized over all purchases very much behind, tossing a good $2k or so into the ether.
A few more expensive repairs (logic board failure due to GPU, top case replacement for butterfly keys, screen replacement from failed coating) were taken care of by service programs free of charge. I find it remarkable that folks have so many issues - most of my Apple purchases have been completely trouble free.
Sure, if you have small children or work in environments where accidents can happen, it makes sense. If you specced out your machine to the hilt where the replacement cost is extreme, it makes more sense. But as a default rule like it seems to be on this forum, I just can't agree with it as all - this or *any* insurance product aside from medical/auto/fire/etc where costs can be exorbitant to the point where it can bankrupt someone, as a good, sensible purchase.