Liquidity, it's a thing. Organized crime is responsible for many billions of dollars changing hands, If One of the Bigger Mexican drug gangs bought in to Monero or Bitcoin, they would not be able to sell their coin at a decent price unless, another Mexican drug gang agreed to accept Monero. Here is why that wont happen. Drug gangs frequently operate in places lacking good internet or cell signals, they like instant transactions, they like not worrying about hacks, lost passwords or misplaced thumb drives. There is no anonymization feature online that is as good as cash yet and should something de-anonymize their transaction history it would be very bad for them. Monero could be perfectly anonymous one day, exploit found the next, such is the risk with any software.