Yeah, IMHO, drugs are a simple "quick fix" people are looking for for issues that are multifaceted and highly complex.
If you want to enhance your thought process !long term!, you should probably avoid any sort of synthetic drugs, be it legal or not. Drugs build dependency, and lead to long term side effects.
Instead, focus on natural things that increase hormones or are known to improve brain and bodily function.
Kudos to the guy that mentioned exercise. Besides keeping you body healthy, it'll release hormones and endorphines which will improve your mood and thought. Same as a healthy sex life. You may become addicted to these things as well
but they are (mostly) healthy for you. All things in moderation.
Spend time doing thought experiments, creativity excercises, meditate, and free-thought writing rather than video games, parties, spending time online, or distractions. This will stimulate your brain.
Finally, if you must, look at natural hormone suppliments which are over-the-counter. Good sleep is more important for brain function than anyone can say. 8 hours of sleep no later than midnight. Here, melatonin can help an hour before bed. Vitamin B and E from sunlight is important for psychological wellbeing. Spend some time outdoors. And omega3 fatty acids from fish oils are said to promote brain health as well.
Anyhow, I hope that helps. There is no wonder drug or quick fix to improving brain function. It's a balancing act you'l be doing for the rest of you life that creates a healthy lifestyle for you and everyone you know.