Like many controversial issues regarding government policy, it's an arbitrary line. Different people's brains are susceptible to addiction to different things.

Like many controversial issues regarding government policy, it's an arbitrary line. Different people's brains are susceptible to addiction to different things. I don't enjoy drinking but I still understand some people struggle with alcohol addiction and that it could potentially be a net positive if alcohol were outright banned. It's pretty condescending to simplify people struggling with addiction as simply lacking self control.