The human race has, and has always had, murderous and destructive groups. Somebody burned the Library of Alexandria. The hordes of Attila the Hun, and later, Genghis Khan, left behind ruined cities and monuments of skulls. The Vikings went home with silver and gold, and left behind stripped altars and ruins. Nihilists threw bombs. Al Qaeda blows things up and crashes airplanes into them.
It doesn’t matter when, where, who, what, or why. Somebody fiercely wants to destroy it. And they only have to get lucky once. If they get lucky in the wrong place, Earth will receive a massive 100,000-kilometer techno-whip around the equator.
Space elevators make a lot of sense — but even if we could, we’d be fools to build one.