How do prescription drugs lead to addiction?

Well drug Abuse the three classes of prescription drugs that are often abused include: Opioids used to treat pain. Central nervous system depressants, like benzodiazepines Xanax, Valium, Ativan, Klonopin, used to treat anxiety and sleep disorders.

So thats only some reasons why they can be addicting.

but im sure there is much much more.!