we need to kill off fire departments. my house has never burned down and i will never get my money's worth.
You're talking a catastrophic level of pain and suffering if there's nothing to take its place.
In principle the US could phase such a system in by redirecting future Social Security payroll taxes to 401(k)s while maintaining existing commitments. But because Social Security is so deeply underfunded, workers would need to keep up solidarity payments for decades without any expectation of reciprocity once they retire.
Still, everyone would be better off in the long run.