The reality is that people make mistakes and they make them very often. Even when they don't make mistakes, they are not always the most responsible. This is why it is important to have laws that protect people from themselves. Seatbelts are a good example. Another is social security taxes.
It is the government's job to make sure the citizens are protected. A lot of times that protection will be citizens protected from hurting themselves. It is very moral to have these laws and I think it would be immoral if you did not have the laws and did not fully protect people.
Hypothetically we could mathematically calculate using statistics the best decision for everyone to make at every second. But then life wouldn't be worth anything. We would be nothing but robots. People should have the right to do what they want if it doesn't infringe on others.
Some make the argument that these actions do effect others. If they effect them enough and that's the reason for the law then you're not doing it to protect people from themselves.
But people too often will make arguments about say cigarette-smoking costing the health care system more money but there are conflicting studies on that. Some studies suggest that cigarette smokers reduce health care costs over the long term by dying at younger ages and so avoiding certain expenses.
Whether the costs outweigh the benefits or vice versa for that particularly case there are likely things people do that hurt themselves that inadvertently help others for reasons like that suggested for cigarettes. And then likely there are things people do that help themselves that end up costing others a lot of money.
You can't have your cake and eat it too. If you support laws against unhealthy or unsafe things because of potential inadvertent financial costs to society you also have to support those same laws against healthy or safe activities that inadvertently cost society more money.
Laws must be founded on consistency or else people will not respect them!
It is our responsibility to deal with the consequences of our actions, not the government's responsibility to prevent us from choosing those actions in the first place. I'll concede that things like taking illicit drugs, eating fatty foods, and not wearing a helmet are dangerous and should never be done by anyone, but the choice to do these things or not should be left up to individual discretion. I own myself; the government does not, and when considering decisions that may be harmful to myself, I am the one who should be empowered to assess the risks and decide, rather than the government doing so for me.
Everyone has unalienable rights and the right to pursue happiness. As long as someone’s rights do not affect the rights of another individual it should be legal. When someone infringes on the rights of another that action should be illegal. Creating laws that protect individuals from themselves is contradictory to liberty.
A modern pillar of democracies is that citizens have the right to life, but if they have the right to life, do they not also have the right to death? Freedom of having control over one's body is also a legal precedent often upheld. While harming myself is probably an immoral act in itself, someone else trying to stop me is also immoral, no matter how well intentioned.