I don’t think GA is shrinking so much as it’s segmented so hobbyists do ultralight aviation such as powered paragliding, used aircraft cover most of the classic GA side of things, and new aircraft are for people or companies with money to burn. On top of this, drones and satellite’s are filling in for some stuff at the margins.

PS: A new set of paragliding equipment runs 10-15k, but it’s more like a jet pack than a traditional aircraft.