A dramatic reduction in cost and increase in effectiveness of some undesirable behavior is exactly when you should look for new ways to address it. The goal of making things illegal is to prevent their occurrence, and if they get suddenly much cheaper and more effective, then your prior methods of deterring them will no longer work.
I didn't say all laws are 100% effective, or even greater than 0% effective. I stated why we have laws at all. Pretty wild logic you've got here. Let's try this one:
> Making murder illegal didn't stop people from murdering. Only a person can stop themselves from doing something, that's not something a law does.
Should we not have rape, murder, arson, or fraud laws?
You're confusing a bad law vs a law you don't like.
Turns out drug laws for adults are bad because a huge portion of the population does them. This said very few would agree that we should start letting kids do drugs.
Nuance is important and many people don't seem to grasp that distinction on things that hit close to home with them.