I would agree with DusterPilot on #1 and #3 but not on #2 as I don't think the average GA pilot choses to fly based on a pilot's potential commercial career. There has to be an interest in airplanes and flying as a youth when dreams are formed and may come to life later. Most older pilots built model planes as a kid and never forgot the hope that you might someday become a pilot flying a real one. But I think that desire has been reduced by a different set of youth interests more aligned with electronic games/videos rather than physically creating a model and working with your hands. Couple that with high flying costs and young people just don't have the interest or resources to learn flying.
We fly about 250 Young Eagles every year in an effort to instill a desire to fly. In 5 yrs of doing this, I know of only 2 kids who moved on to take lessons and obtain a license. Wish it were a higher ratio.
Bob H