A drug dealer is a person who sells drugs, particularly illicit or illegal ones. Dealers' most common reasons for joining the business are desire for money and respect, although many are selling drugs to pay for a drug habit. This risky form of employment is most common in poor and especially urban areas, where people have little hope for improving their lives or living with dignity within the accepted social channels.
This is a hazardous occupation for a number of reasons. First, because the transaction and products are illegal, the police are liable to shoot at drug dealers or put them into small cages for 8 to 10 years. Secondly, people in gangs or the criminal underworld also tend to be drug dealers, tend to be territorial, and tend to have guns.
Despite these hazardous working conditions many street level drug dealers don't make much money. Drug turf tends to be controlled by a gun toting crime boss who employs street dealers to sell drugs while taking the largest part of the profit. This is particularly true of hard drugs such as heroin and cocaine. This is less of a problem in non-neighborhood urban areas when selling softer drugs such as marijuana, lsd, and similar largely non addictive substances.
Drug dealers tend to be vilified far more than they deserve. Many are people trying to make a buck. Many are people tired of a limited supply of drugs in an area or group of friends who decide to deal with limited supply and lack of drug money in one fell swoop. OTOH many others would shoot their own gramma for just about any monetary gain.
When dealing with dealers a good thing to remember is that cocaine, heroin and pcp dealers are infinitely less forgiving than most credit agencies. Your best bet is to either befriend a drug dealer before becoming a client. In general, people who sell drugs for a living tend to be more dangerous than people who sell drugs to pay for drugs.