As a Brazilian I will forever resent all the pain and suffering caused by a misguided (and malicious) notion of how all of this should work. It was pushed by a Puritan view of the world coming out of the US in the 60s onwards, and even worse: this was pushed down the throats of other nations due to internal US affairs, the counterculture movement and so on.
It's extremely dirty and spread so much suffering across the world that I hope it will be seen as it is: a tyrannical and oppressive decision peddled by conservative inhumane and non-scientific people, steering whole generations of the world into despair and suffering to play politics. It is a protogenocide of mental health sufferers, worse that it's been layered into these policies trying to be sold as solutions.
How do you expect the US to force Colombian domestic policy otherwise?
Also next time you suggest/imply that U.S. has control over another nation's domestic policy, at least spell the country's name correctly.
If this measure helps to get to a lasting peace in the country by allowing the FARC and remnants to cultivate and have a living, then you also need to factor in the costs of the long running internal conflict and all the military spending and lack of growth due to insecurity that the country has suffered.
The Drug War has had massive collateral damage on the country, and in purely economic terms there is much to gain from ending it.