Why do pilots earn so much?

On average, even a beginner can earn more than 10-20k dollars a month. Money that big, are paid for a reason. According to specialists, pilots-to-be face high demands, because it is a job, that requires a lot of responsibility. Also, pilots must attend special training every few months even after they are hired, to check their existing knowledge, and learn to immediately react to dangerous situations and know how to resolve them, such as an unexpected fire, or a failure in the engine.