Sorry but it doesn't work that way. Unfortunately we DO have to draw some lines for the good of our civilization & locally, for the public. Research and common sense tells us which ones. Sure, cars kill & knives kill, but they're pretty useful & generally ok. You won't convince me that it's essential for anyone to be allowed to buy more weapons of mass destruction (more than they already do) for example, & yes, I favor banning assault weapons...weapons of war just don't belong on public streets no matter whose pitiful ego thinks they do...and the government is there to put limits on those things are are the most harmful to public health. Debates will go on...with the ones making money off such products are the ones pushing the hardest to keep them legal.
Let's talk about how cigarettes have been handled in our world: for many years, non-smokers were forced to inhale the smoke of others in work places, restaurants etc.Even now that most places have gone non-smoking, streets are still littered with cigarette butts & people who enjoy smoking still stand around the doorways of businesses where they are not allowed by law to smoke (FYI, smoke adheres to the hair & clothing of non-smokers that have to walk thru the clouds of smoke!

Many of us prefer to take breathing seriously & would rather not reek.) AND burning butts tossed from vehicles along roadways still start massive brush fires that burn down peoples houses, ruin wild lands, kill wildlife, and guess what, we ALL pay for the damages. So the things that "the rest of us" pay for is not limited to the medical care of indigent patients, or those who just don't think they "need" medical insurance.
Just because we can't stop people from over-eating or every other conceivable act of self-destruction doesn't meant that nothing should be banned or restricted in a civilized country. If you cannot tolerate a few rules meant for the "good of all" then I'm sure there are still places you can go live off the grid & no one will know or care what you do.