In your free country, am I free to not pay for all your good ideas? What happens to me if I refuse to contribute to your ideas?
It could perhaps be offered as an emigration option to people who are opposed to paying into a system that everyone will benefit from.
Depends where you live. In most European countries, as long as you are a resident with a legal address, past a certain amount of time lived here, you're expected to contribute a certain proportion of your earnings as taxes to fund all public and social services.