Eh, smoking has declined in the US despite marketing. But even if you accept that addiction will go up, the deadweight loss of putting people in jail is enormous compared to spending that money on treatment and education.

Rates of alcoholism went up after prohibition but alcohol-related crime went way down.

Also, I've always thought this comic about Milton Friedman's predictions about drug prohibition explains the issue very well:

http://www.stuartmcmillen.com/comics_en/war-on-drugs/