One drop and you pay around the same price, well slightly less, as having Apple care so if you are a fairly careful type like me, you would just save that money by not having it in the first place. Even under Apple care when my cousin went for her old 6S battery replacement due to a battery fault they replaced it only after confirming her phone was randomly turning off, otherwise if its within normal usage/cycles they wont replace it unless its like below 80% charge efficiency which depending on your use may occur after the extended warranty period anyway.
Guess it depends more on how careful you are, if you have a history of breakages/carelessness definitely buy it, will save you a lot, but for my usage if I had paid that much in extra warranty fees for every smart phone I owned it would have been a waste. As one of the people above said, extended warranties are nice money makers for companies as most people never utilize them.
Sometimes carriers have better warranty offers and if you have purchased the phone using AMEX and some other credit cards they automatically increase your coverage period by 1-2 years, so check on that as well.
A good carrier example in my experience is T-Mobile, they once temporarily added insurance for a few days (just for replacement purposes) and gave me 7 overall replacements for my Sony Xperia Z3 6 of them after 8 months from purchase shipped overnight each time, so I didn't even have to deal with Sony.