I don't know what you mean by first hand knowledge, no, I didn't play college baseball, but I had many friends that did (and were drafted out of high school and college).
My point is that if a kid was going to get $1.5million from the Red Sox, he isn't going to be pay $20k to play at Ucla. He would take the ride, but not pay out of pocket.
I am also not contending that 11 players get 11 scholarships, my point is that the "superstar" as you like to say will get the full ride. There is only, maybe 3 superstars, on a team. So, at most, 3 guys will get full rides, the rest (8.5) will be split likely among 15 players, the rest would be walk-ons.
I'm full aware of the eligibility rules for the draft. To add to your point, a player could leave as a freshman, transfer to a JC, then get drafted as a sophomore if you want to get more specific.