as soon as they find a way to make billions from it legally it'll be legal
It's actually sort of the opposite. They know and we know that American hemp would be a multi-billion dollar industry, and they'll do all they can to prevent it.

No one (besides maybe Anslinger) did more to criminalize cannabis than William Randolph Hearst, who had his stake in the lumber industry, which would have (by now) been non-existent due to the potentials of hemp.

Fast forward to the present, Big Lumber still knows this. Big Alcohol still knows that an alternative mainstream (haha) psychoactive would hurt their business. Big Tobacco still wants their product to be the only smokable you can legally get.

Perhaps most embarrassingly, Uncle Sam still knows he's been pushing lies and dropping dimes for too long to backpedal now.