Drunk drives kill more people then people with guns but you can’t displace one with the other can you? Now if we displaced dopers with responsible beings you may have a solution :)
It also makes no sense to say pot does not displace booze. All intoxicants are positively known to displace others in the market and among users. For example, the "success" of cracking down on pot along the Mexican border recently has increased smuggling of higher-value drugs like cocaine. Brewers fear pot because it is a mild recreational intoxicant, grows like a weed (nobody actually needs to buy pot - it is as easy to grow as tomatos), and probably would displace beer. Prohibition vastly increased drinking of gin, rum and other hard liquor. Your example of guns not being able to replace cars is laughably inapplicable and irrelevent to actual documented events where one drug was displaced by another.
Do you have a workable plan for ridding the world of people who want to get a buzz on? And where in the Constitution does it say the government is allowed to tell adults what they are allowed to consume?
The failure of the Drug War is just another example of how the Founding Fathers were 100 times smarter than today's jackasses like Asa Hutchinson. Don't TRY to tell adults what to consume, they will naturally choose the least harmful path.