The WWI surplus market really hurt postwar business.
Why buy a new two seater when you could get a surplus Jenny that the Government bought for $8000 in 1917 for $500, and why rebuild an OX-5 engine for it, when you could buy new crate motors for scrap aluminum price?
Yes, it was boom and bust. The surplus pilots were reduced to stunts and barn-storming to make a living from the skills they had, Even aircraft development would have been suppressed with the over-supply of cheap equipment. The biggest impact is that people had less money and it was only worth half as much.