However if your position on this is based on a liberal ideal of people being allowed to do what they want, then it should surely equally apply to the taxpayers (particularly if they are majority voters) who don’t want to pay for the decisions of others.

Taxes have forever been an exception to the liberal idea of freedom to do whatever. They're a social and economic necessity.

Taxpayers decided to fund universal healthcare. If we start picking and choosing who is "deserving" of that care...that's a terrible precedent.

In several ways, a cigarette ban is an exception to how democracies have traditionally dealt with issues around freedom. There's really no precedent or defense for it except that cigarettes are currently unpopular.

But even if you discredit the taxpayer funded health argument, there’s moral arguments around selling addictive substances, human pain caused by premature death and sickness etc.

And I think it's nearly universally acknowledged that ceding to the government the power to decide how its individual citizens should live their lives is a terrible idea. If we were talking about almost anything else, there would be an uproar. Government says religion makes no objective sense and causes a lot of fighting and mental stress, decides to ban worship. Uproar. Government decides that having children when you can't afford to offer them a good life is immoral, decides to ban children for poor people. Uproar.

A cigarette ban only feels like it makes sense because it's cigarettes. Copy the justification for the ban to anything else and you realize how bad an idea it is.