The problem is once we decide we want to control behavior that really doesn’t involve others. We started down the path with Prohibition, then that got repealed. Government loves power.
But government of any kind—short of anarchy—always controls individual behavior. It’s a matter of degree, and it’s the price we all must pay to live in civilization. Why? Because no one is an island. The things you do in private often can and do affect others. So even if I agree pot should be legal, it’s something that needs considerable safeguards to limit the damage to society.
Libertarians on pot sound like pro-aborts on abortion to me. All they seem to care about is their own, selfish rights, not the rights of anyone else who has to deal with the societal problems created in the process. And even if a particular individual is a responsible pothead, the ready availability of high potency THC products are not used responsibly by many others, creating issues for the rest of us to deal with.