Yes let us look at the Netherlands.Look at the Netherlands for proof that it can get worse.
Last time I checked a few years ago Netherlands High School (No pun intended) Seniors have tried pot are about 5% in the US it is about 60%.
Do you really want to go into the crime rate in US cities versus the Netherlands ?
The Netherelands also have legalized prostitution.
Do you really want to to into sex crimes difference ( rapes, molestations, child sexual abuse ) between the Netherlands and the US. Last time I checked all were much lower in the Netherlands.
Banning any inanimate object is IMHO ineffective and useless.