Weed is illegal because the govt can't tax it?

That doesn't really make sense that the govt would keep it illegal because they can't tax it because isn't like millions of dollars being wasted on the "War on Drugs"? So isn't the Govt like losing money by criminalizing it? What am I not understanding?

America's first marijuana law was enacted at Jamestown Colony, Virginia in 1619. It was a law "ordering" all farmers to grow Indian hempseed. There were several other "must grow" laws over the next 200 years (you could be jailed for not growing hemp during times of shortage in Virginia between 1763 and 1767), and during most of that time, hemp was legal tender (you could even pay your taxes with hemp -- try that today!) Hemp was such a critical crop for a number of purposes (including essential war requirements - rope, etc.) that the government went out of its way to encourage growth..................... The first state law outlawing marijuana did so not because of Mexicans using the drug. It was because of Mormons using it. Mormons who traveled to Mexico in 1910 came back to Salt Lake City with marijuana. The church was not pleased and ruled against use of the drug. Since the state of Utah automatically enshrined church doctrine into law, the first state marijuana prohibition was established in 1915. (Today, Senator Orrin Hatch serves as the prohibition arm of this heavily church-influenced state...................................... states quickly followed suit with marijuana prohibition laws...