It's only causing more problems and violence.

Well, I guess that depends. There are some substances that are much more dangerous than others, and some of the more harmless ones should be illegal.

It's much more trouble than it's worth to try and regulate usage.

Alcohol causes many times more problems/death than marijuana.

This is a pointless waste of tax payer money. for one it makes people want to do it more because they are told over and over again that they can't do it. Another reason is because it puts more people behind bars for small crimes and tax money pays for court fees lawyer fees and housing of the prisoner.