What is the popular explanation of Murphy's law?

If there are two or more ways to do something, one of which will lead to disaster, then someone will make this choice. Its basic content is: if things are likely to go bad, no matter how small the possibility is, it will always happen.

Case:

Murphy is a captain engineer at Edwards Air Force Base in the United States. 1949, he and his boss, Major stapp, had an accident during a rocket deceleration overweight test due to instrument failure. Murphy found that the measuring instrument was installed backwards by a technician.

From this, he learned a lesson: if there are many ways to do a job, one of which will lead to an accident, then someone will do it in this way. At the press conference afterwards, stapp called it "Murphy's Law" and repeated it in a very concise way: everything that can go wrong will definitely go wrong.

Legal sources:

In 1949, an engineer named eddie murphy, an air force captain, played a casual joke on one of his unfortunate colleagues: if something is likely to be done badly, it will be even worse if he is allowed to do it.

At first, a harmless joke didn't mean anything, just said the helplessness brought by bad luck. Perhaps because there are too many unfortunate people in this world, or because people always make such mistakes, this sentence spread quickly and was finally interpreted as: if bad things are possible, no matter how unlikely, they will always happen and cause the greatest possible loss.