Well, my friend's S7 cracked itself overnight. My S4 cracked twice due to dropping it on the floor, both times I had the screen replacement. My current S7 fell frequently, but is still mostly intact. As far as I can tell, everyone in my immediate family cracked their smartphone at least once over past few years.
Beyond dropping, as far as I can tell, there are two other common causes of screen breakage. One, sitting on it (a lot of people carry their phones in their back pockets, which is something I cannot understand; beyond accidents, this makes them vulnerable to pickpocketing). Two, women sometimes crush their phones in their purses (especially when they are in hard covers that act as levers when an item gets between it and the cover).
Beyond dropping, as far as I can tell, there are two other common causes of screen breakage. One, sitting on it (a lot of people carry their phones in their back pockets, which is something I cannot understand; beyond accidents, this makes them vulnerable to pickpocketing). Two, women sometimes crush their phones in their purses (especially when they are in hard covers that act as levers when an item gets between it and the cover).