How is smoking pot any different from eating candy? Neither of them are physically addictive, both of them are psychologically addictive. Both of them have no benefit other than to activate reward pathways. One of them is the desire to taste something delicious set off by generations of evolution, and the other is the desire to taste a delicious state of mind set off by your apathy with your current state of mind, so the only argument that remains is whether or not naturalism is more "valid" than chemical interactions, and that's just retarded.