Of course, this is all a drastic oversimplification. Rookies can get jobs, and get some experience by exposure. But developing talent effectively & efficiently takes more time & resource investment beyond just having them do work, and that's investment with an uncertain and non-immediate return. It's a tough nut to crack, but the place where I would start is figuring out how to retain your good employees, especially when the growth of their market value is faster than your company's standard career advancement path.