Killing your junkies don’t make sense. Even with small dealers they know how much they can ‘lend out’ to their clients. After the client gets to the point they get cut off. But they will have 20$ next time. You will give them 10$ material and keep the other 10 for their loan.
How they got the money, you don’t ask. Customer service even in drug business is the key to long term success.
And sometimes people who went to jail come back months later, because they hit big and they can afford to pay back that 16$ that you never thought you will see again… and then spend more money that you didn’t think they had.