Actually, that's only 207 million dollars. 22 billion would be, literally, 100 times more impressive.
And I think they certainly wouldn't have had that much money if drugs were legal. The illegality of drugs creates the black market for them, and their willingness to use violence in an unregulated market is what gives them market share. Without drug laws, there would be open competition and prices would fall, cutting profits for the cartels. In this sense, it is prohibition which creates violent drug cartels, the same way it did with bootleggers during alcohol prohibition in the US, where Capone and his gangsters made his riches doing the same thing.
+Nucky Johnson, Bugsy Siegel etc. Prohibition was the biggest opportunity in 30's. Since last 80 years drugs are the best way to make ridiculous money.