Much of the time, when someone is arrested on drug charges, the root cause of the problem is actually an addiction. That individual didn't want to buy the drugs or use them, but the addiction made it so they felt like they had no choice.
This is especially a problem with the recent opioid epidemic. Many people get hooked on opioids when they use them for medical purposes since these are very useful and effective painkillers, but then they can't shake the addiction afterward. This leads to overprescribing, illegal use, overdose deaths and many other issues.
There are those who would still say that the individual shouldn't have become addicted to the substance in the first place. But this overlooks the fact that addiction is recognized as a substance use disorder that can stem from completely legal prescription medication use. Medical experts describe it as a “complex disease of the brain and body that involves compulsive use of one or more substances despite serious health and social consequences.”
Addiction sets up a system where your brain is always seeking that reward, and you can suffer physical, mental and even emotional withdrawals if you don't get it. This is incredibly hard for people to overcome on their own, especially with drugs like opioids.
The social consequences are quite clear when you consider someone becoming being arrested for drug possession or use. They could have to spend time in jail, they could be ordered to pay fines, they may lose their job and there could be a lot of other ramifications. This is why it's so important for people who are facing charges to understand all the legal options that they have.