First of all, before adopting such dangerous laws, one must think whether this will be useful for your children.
I'm quite sure it it will be. I wouldn't want my child to be put in jail with murderers and rapists for smoking weed at a party.
The unfortunate fact is the global economy is completely dependent on illicit drug money. If this money was cut off the global economy would collapse. This is why it is opposed so vigorously.
The sad reality is we're living a lie. If you asked random people in the street they'd be against legal drugs because of all the fear the media has put in their heads. The society is brainwashed.