In 1987 there were 827,000 pilots in the U.S. Today, there are less than 600,000. Where did they go? How could they go when air travel has increased quite a bit?
Part of the reason is that the Air Force in the 20th century trained about two-thirds of the pilots. This was before today's use of drones by the military. Now, most pilots have to pay for their training, which exceeds $100,000. The 1978 Airline Deregulation Act and 9/11 wreaked financial damage to major legacy airlines, five of whom declared bankruptcy.