I've been trying to not respond to this thread the entire time but cannot resist anymore. Haha.
I was diagnosed with ADHD when I was little and take an XR every morning. Taking it, I have to be extremely careful because it has some pretty bad side effects on me which I need to be very aware of so I can recognize the signs early and do what I can to help minimize them. I actually physically feel better not taking the medicine because then i don't have to worry about side effect management, but my ADHD is pretty bad so it's necessary to take it. I don't see any substantial value to it if you don't have ADHD, because a person is not cultivating needed study skills and habits on their own when tackling something huge like the MCAT without the use of a drug.
The bottom line is that with any drug, it runs the risk of dependency. How great that risk is can of course be debated, but I personally feel that someone who is taking it illegally early on can be setting themselves up for severe dependency later on especially if they're looking at medical school, residency, etc.
In the end, if you're going to take it without a prescription you're running a huge risk so you need to be very careful and manage how often and under what circumstances you take it. Those who aren't prescribed and decide to not use it I feel are making the smart decision because they are reaping the benefits of hard work without added help which is setting up a great foundation for later on without all the risks and side effects of taking a drug that isn't prescribed to them.
So yeah, OP I think you're making the right decision. To each their own, and quite frankly i feel that someone can take it as they deem fit. It's their decision and their responsibility, but with that being said sometimes a person makes the bed and has to lay in it so I wouldn't be surprised if it came back to bite them eventually. Especially if they're not just taking it on the day of the MCAT, but in the many months leading up to it to study for it. That sounds really risky.