Answer:
The Nature of drugs
Step-by-step explanation:
Drugs are addicting, it meant to be like that. The effect is to create cravings after usage and it can last long, making it hard for human nature to stop giving up the usage of drugs.
Now think in economic terms. There is a high demand of drugs ( because of the addicting nature of it ) and there's limited supply of it ( cause in most countries, it is made illegal to trade them for money ), put them together, high demand and low supply of drugs, this would mean the price of drugs must be high. Greedy is in the human nature, so it would create an incentive for drug trafficking as the rewards are high.
Hope it helps.