I think that the cocaine trade and heroin trade are really different. At the time, when the Medellin cartel were the top cartel in the world, they were the producter of cocaine and the distributor.
While, for heroin, the italian mafia were probably the top distributor in america, but they were not producer of heroin.
The producer were people from asia. Countries like vietnam, thailand and afghanistan.
sicily was full of heroin labs at that time, the biggest produced 6 tons yearly, and it was distributed in both europe and united states
also, the colombians at that time had not a big networks of distributors like sicilians had in europe and united states, so the earnings diminished because the drug passed through too many hands
