This is an interesting argument. From a libertarian standpoint, I have the freedom to take whatever actions I want, so long as those actions don't interfere with the freedom of others.

Now, science is not a zero-sum game, but school is. There are a limited number of spots in top universities, and the pressure to get one of those spots is enormous.

So if my peers are all using study drugs, then I would be compelled to use those drugs to remain competitive. So their use of the drugs would interfere with my freedom of choice.