Drug gangs need to be deregulated - Absolutely. Drug gangs are granted a de facto monopoly by the government through its enforcement of anti-drug laws.
The cost of doing business as a drug dealer is too high - Going to prison is a high price to pay for a job that actually pays little and offers little in terms of upward social mobility.
Most people do not understand how drug gangs work - Probably true due at least in part to media depictions of wealthy drug dealers sitting in palatial estates in Colombia.
(Some) poor people do not understand the employment opportunities available to them - Applies to most if not all income groups.
McDonalds pays its workers too much - Seriously, how hard is it to not put ketchup and cheese on a hamburger?
The turnover rate among crack-sellers must be very high - Again, the prison thing.
OK, now the one I didn't vote for:
Legalize crack so we can tax it and raise the price, to combat the drug problem - The high price of drugs is the problem. By driving up the price, you create more incentive for people to join the drug trade. You also create more incentive for addicts to steal in order to fuel their addictions.