These students are making a tradeoff between an abstract notion of "cheating themselves" and a very concrete notion of "having a worse GPA". The second one translates obviously and directly to job prospects.

they should learn as much as they can + cheat for optimal results

Not really. If they got admitted to Stanford to begin with, they are smart enough to succeed if they put in the work. So what they are actually trading off against is "I don't want to do the work", which is far less defensible than your reading of the situation.