Conversation:

You go to the medicine man and tell him you feel bad - he drills a hole in your head. He asks if you feel better. How likely is it you're going to say no? You want he should drill another hole, already?

Actually, yes. A skull was found that had been trepanated several times. Apparently some primitive people found the effects of trepanation so desirable, they had several.

Or maybe they were too stupid to say "yes?"

The South American tribes - like the Incas and Aztecs - were users of the technique and certainly weren't stupid. These guys were not "ug-ug" cave men, and skulls have been found with a plethora of partially regenerated cranial holes.