But that's not how it's used. Higher THC levels are used to create faster, more intense highs. Well beyond that of simple buzzes from the original very low levels of THC traditionally present. If your statement were true, the volume of pot consumption per person would have been in steady decline. When in fact it has steadily risen. People are consuming much higher levels of THC and more frequently.
Starting from the 60s, there was lots of focus to significantly increase THC levels in pot. It has steadily increased ever since. Prior to this there were modest efforts to do this but they generally didn't increase very much simply because in the western world there wasn't a serious "pot culture." It was simply something one did from time to time. Sometimes even medicinally.
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