So why would a pro-drug Libertarian vote for a Conservative?
There are rightwing libertarians who find the paramilitarization of police forces, no-knock raids, and civil asset forfeiture without even the benefit of a charge let alone a trial, more of a threat than the drugs against which the war on drugs is reputedly being fought.
Assuming they’re all potheads and druggies is a mistake, therefore.
Because most of them don't take drugs, but they do pay taxes. Most libertarians I know are straitlaced workaholics. What they hate is wasting law enforcement resources on victimless crimes when there are lots of thefts, robberies and rapes that could be investigated in greater depth instead of being dumped into cold case files. Some of the money saved from not imprisoning perpetrators of victimless crimes could be spent on longer sentences for thieves, robbers and rapists. Their perspective is that the state should not be shoehorned into the parental role - that role is best performed by each individual's actual parents.