I'm a smoker so when I get cancer I'll refuse to pay for my treatment.
That sounds like a bad idea. Why would you want to refuse the payment?
I believe it's my own problem and if I get cancer from smoking, so be it.
Refusing to pay for your treatment after you decided to consciously do something as bad for your health as smoking is a very immature way at looking at life. You need to own up to the mistakes you've made and be willing to pay for any treatments if you ever do receive cancer from your smoking.
My cigarettes work to make me calm. So they aren't causing me any harm. Even if they are causing bad things to happen, I don't think they will affect me.
You need to try to break that bad habit and own up to your own mistakes.