Why could being smart all the time be bad? Well, what they don't tell you is that it never stops. Even if you want it to. As you age those discovery rushes get.. Tiring. Exhausting. Irritating. I suspect that the neural pathways easily get exhausted and depleted of those cannabanoid related chemicals. I can tell you that a bit of pot really does alleviate a whole lot of mental exhaustion.
Really. My mind is constantly on the move and learning, but I certainly don't find the simple fact of it exhausting. I also don't need drugs to give me a break.
Logic is the chastity belt of the mind!