What is so inherently criminal about drugs? What has criminalizing it done to deter it's use?

I am actually drug free, but I am all about the legalization of drugs. Unfortunately, if that happened in the US many people would lose jobs (think about it !! coast guard, beat cop, and even your friendly Crack dealer would lose his job). Say what you want but the trafficking and selling of illegal drugs is a HUGE PART of our economy. I am not saying its safe by keeping them illegal, but it does keep the money flowing. However, in terms of legalizing I just have one word!! AMSTERDAM!!!