If you car's brakes can't slow you down from a high speed, you could crash and die. If the balcony on your home can't hold your weight, there could be serious injuries. Small parts on a toy could lead to your infant choking to death. This is why many products are stress tested before they're made available to the public.

From Wikipedia:
Stress testing (sometimes called torture testing) is a form of deliberately intense or thorough testing used to determine the stability of a given system or entity. It involves testing beyond normal operational capacity, often to a breaking point, in order to observe the results.

A car or balcony design which fails stress testing is sent back to the lab to be re-worked. Something is wrong with its makeup, and those issues must be resolved before the car is marketed. The last thing Toyota or Nissan wants is a car falling apart or malfunctioning out on the road. That's a lawsuit waiting to happen. Even laptops, phones and toys are stress tested before they get to us.

Humans get stressed tested too.
Stuff happens that's the opposite of what we want. Plans fail. Normal circumstances turn anything-but when we least expect it.

The difference with people is, a (surviving)human who fails a stress test still moves forward to the next station in life. This person is usually unprepared and under qualified to be there. The hard part is, the next stress test will be even rougher and even less forgiving. And it keeps going, until the product (person) breaks.
When was your last stress test? Maybe you're in the middle of one right now? No matter how you deal with it, you'll be moving on to the next level - and another test coming.
Will you be ready for the next one, or even more unprepared?