That’s because statists always have their pet issues where they are willing to abrogate their own principles. First of all, marijuana doesn’t destroy many people’s lives, alcohol probably wrecks more (again, why are we holding substances or objects rather than PEOPLE accountable) than almost any substance out there, even if the proportion is somewhat smaller than other drugs.
It is also interesting to note that most of the same concerns and psychological projection involved in the War on Guns is the same as that employed in the War on Drugs. Both are about freedom and in this country we had far less of a problem when both were extremely legal than we do now that they are regulated (guns) or illegal (drugs.)
Families are also destroyed by other things, ignorance, sadism, psychopathy, overeating and morbid obesity, the death of a child from an accident or illness, etc. Let’s ban and arrest millions of people to make it right!
I would bet that more families are destroyed by the lagal penalties associated with pot than the use of the drug on its own.