Cost/benefit. The procedure is not free, and there are harms associated with the procedure that are unlikely, but push it into negative ROI. In particular pay attention to the risks of the procedure; it’s not common (neither is colon cancer in young people) but people do die of complications from the colonoscopy.
I actually saw some discussion a few years ago saying that the procedure is a net harm in all age groups if there are no symptoms/genetic predisposition, trying to dig up a ref and could only find https://www.cancerdefeated.com/the-tragic-risks-of-a-colonos... so I might be misremembering that detail.
I actually saw some discussion a few years ago saying that the procedure is a net harm in all age groups if there are no symptoms/genetic predisposition, trying to dig up a ref and could only find https://www.cancerdefeated.com/the-tragic-risks-of-a-colonos... so I might be misremembering that detail.