Well, while I agree that the whole "conservative" ideal system slants a large portion of America against drugs, it isn't the real reason why drugs are so hated.
Drugs are hated because the people in power realized they were bad for business. That's why alcohol and cigarettes which are absolutely, 100%, for sure, known killers are sold like crazy to Americans and shit like weed and LSD are so illegal you face serious jail time for ridiculously small amounts.
Marijuana was actually made illegal because it interfered with the paper industry which was run by William Randolph Hearst. It also interfered with the cotton industry, tobacco industry, and several others. These folks in power used their influence to get marijuana controlled. Then, to promote that idea the government started associating marijuana with minorities, Mormons, etc.
As with anything related to human history, it all relates back to the dollar sign. I'm no religious nut. I don't go to church. But, I always find it hilarious how everyone blames EVERYTHING on religion. The Crusades? Not about religion. All about rich land owning nobles in Europe wanting to expand their influence and wealth in the Middle East. Marijuana being illegal? Not about religious persecution. All about big business in America and controlling the populace.