Exactly, that's why "punish murderers" doesn't work, because there will always be people that murder others
Exactly, that's why "ban these certain drugs" doesn't work, because there will always be means by which people will get those banned drugs.
Your argument contains several fallacies.
First of all, the "take away the guns" method is a matter of averting disasters via prevention methods.
Your implication that the same logic must apply for "punishing murderers" is flawed, because that deals with what you
do once the crime has
been committed, not how to prevent it in the first place.
The logic behind "banning guns" is to prevent gun-related crimes by limiting access to firearms in the hopes that people with harmful intentions won't shoot up places, but the critical flaw behind that kind of law is the fact that black markets will always exist and continue to offer weapons, and the people with truly harmful intentions
will seek them out, and go to rampage on populations of unarmed law-abiding citizens. If law-abiding citizens are armed, then any attempted assault by a madman with a gun is easily extinguished by other armed citizens.
I do see the validity of your comparison of banning drugs to banning guns, however, and I think it's worth a look.
Regardless of whether or not there are drug or gun laws, wicked people will always manage to access both guns and drugs one way or another. It's then a matter of how you prevent an ensuing disaster that comes once the wicked person has the guns or drugs in their possession.
Laws that ban dangerous and addictive substances and regulate useful prescription drugs are good because they prepare society against potential drug-related disasters.
Laws that permit average citizens to arm themselves are good because they prepare society and families against potential gun-related disasters.
With many drug laws, families that want nothing to do with these harmful substances are more easily protected, while without these drug laws, they have to go through society surrounded by narcotic and addictive substances. Their children are easily enticed by the promise of a good time with a joint of weed and end up in a self-destructive cycle of addiction.
With many gun laws, families that want nothing to do with gun-related crime are unable to sufficiently protect themselves.