The top kids go en masse to Duke, UK, and KU. It's just the way it is. They know the previous year's batch will be gone and they can all collectively walk into a starting spot, be on a contending team for a year, and then go cash their NBA paycheck. Everyone else hopes to grab one or two of those type of guys here and there and hope they can make enough of an impact and mesh with the other guys there for real success to happen before they also move on. A few schools get more of those type of kids than others. And those that can't land them very often make due trying to mold teams with 4 year guys (or 2-3 year guys who developed more than expected, as seems to be the case with Beilein).
And yeah some of those programs are cheating to get those guys.