Quite frankly, I don’t care if some people want to smoke pot. And, I don’t want them to go to jail either. I also don’t want to pay for their rehab or give them preferential medical treatment. When they want treatment, they will have to rely on the charity of their neighbors.
Ditto
Mark Stern once said that it's impossible to be fiscally conservative while simultaneously socially liberal.
Your argument falls into this trap.
Charity will pay for only a small part of the rehab resulting from the pot-headedness that your argument permits.
Instead, taxpayers will pay for the bulk of the rehab, either through outright taxes (obamacare) or rising medical insurance premiums to cover the increased rehab usage.