No mechanical system is ever exploited at 100% capacity. The elevator in your building never has to carry more than half of what it's absolutely capable of. Any kind of building is built with materials that can withstand a lot more than the average load. Your computer never has to work at full capacity - I doubt the CPU's temperature ever reaches past 70C, far from the ~100C at which it can still perform reliable calculations, but also well clear of the ~105C at which the magic smoke escapes.
Smart people don't exploit systems operating at their absolute limits.
Smart people don't exploit systems operating at their absolute limits.