I'm not
unsympathetic to this point of view, but I don't think you realize that there's an
internal inconsistency in your
argument: you say that you should be able to do whatever you want, "
as long as I don't harm others." This, in itself, is a
rule, and a damn big one. In fact, you could argue that it forms the basis for a large portion of our
legal system.
The question is, do I (or anyone else) really trust you, a person I've never met, to decide which of your activities are risky to others and which are not? I mean, you say you should be able to do meth. OK, but can you drive while you're under its effects? Maybe you think you're a super great driver, and maybe under meth's influence you'd think you're an even better driver. Should you then be allowed to get on the road and collide with my car? According to the criterion you set out above, probably not.
Of course, do we really trust our government to decide which things we can make judgments about and which things we can't? It is between these two extremes that human society tends to oscillate, in my opinion. I doubt it's a problem that has a discrete solution, so I guess we just have to live with it.
BTW, you may enjoy On Liberty, which expounds the Utilitarian philosophy of John Stuart Mill. Beats the hell out of Sally Jesse Raphael.