[probably_wrong]

I'd like to point out that your amendments do not solve the problems you mention, as they fail to include how your choices affect others. A variant of the two-body problem, if you will.

Let's pick drugs. Half of the drugs regulations deal with keeping you from killing yourself, which your approach would simplify (although sounds like a variant of "let's solve stupidity by removing warning labels and let the problem sort itself"). The other half, however, is how this change would affect society as a whole, and drug addicts are a burden on society (see: homelessness, hospital costs, correlation with violent crimes, impaired drivers hurting others, etc).

Of course, we know you would never become a dangerous addict lying in the streets arguing with yourself, but you can be damn right that I almost certainly would. And that's why, as I see it, Society (represented by the Government) jumps in and says "no drugs for either of you".

The other points follow a similar line of thinking.

[sneak]

"Some people are irresponsible" does not justify the universal deployment of terrible and profound oppression such as you describe.

Indeed, we have attempted it. Remember prohibition? We still have myriad addicts, have wasted unconscionable amounts of money, and senselessly ruined staggering amounts of lives attempting to pretend that society has claims to or on the physical body of an individual.

If the "burden on society" argument was in any way real, cigarettes and alcohol would be outlawed. It's simply a red herring.

[jkrems]

I'm not sure about the US, but in Germany at least heavy taxation of cigarettes and alcohol is justified by "burden on society". There are more than two options (not do anything vs. outlaw).

[enriquepablo]

> (see: homelessness, hospital costs, correlation with violent crimes, impaired drivers hurting others, etc)

Those are consecuences of being outlawed, not of consuming substances. Blame the prohibition and not the substances. The proof of this is simple: just compare. Compare people drinking coffee today and in 19th century Russia (where it was prohibited). Compare people drinking alcohol today and in early 20th century USA. Compare people using opiates today and in the roman empire...