Depends on the type, dealing drugs is like any other sales job, except way higher risk. Distributing cocaine is as complex as any other distribution job but you're not allowed to use established transportation methods and people might shoot at you. You've got to be a real self starter and creative thinker if you want to be good at it.

Then there's the contract negotiation where nothing is legally enforceable and personnel management where your employees could become addicted to stealing from you. It sounds way harder than my job.