Jonesy

If we continue using marijuana, over the course of 10,000 years, we will form something like a symbiosis. It is likely all side-effects will be gone and the substance will be a useful tool.

If you had a time-machine, and you used it to give knives to cave-people, the cave-people probably would injure themselves and others. But today, we mostly use knives for the useful tools they are.