The article mentions selling the cocaine within Colombia, and to pharma companies for research. Presumably they'd think long and hard before selling it for recreational purposes in markets where that's illegal.

Venezuela is already a narco state, no invasion there

How is it going within Venezuela these days? Might that have anything to do with its relation to the US? Invasion isn't always the right measure. Invasion is the most expensive and most visible measure and the measure that is most frowned upon. The US has no interest in doing that, I think they learned their lesson. But there are a lot of other ways to retaliate.