Sometimes, at scale, interventions save lives. You can thumb your nose at that, but you have to accept the cost in lives and say you’re happy with that. You can’t just say everybody knows best and the best will occur if left to the level of individual decisions. You are making a trade-off.
See also: seatbelts, speed limits, and the idea of law generally, as a constraint on individual liberty.
Constraints on individual liberty as it harms or restricts the liberty of others makes sense. It becomes nannying is when it restricts your liberty for your own good. it should be illegal to drive while drunk because you will crash into someone else and hurt them, but seatbelt laws are nannying because the only person you're going to hurt is yourself. And to get out ahead of it, if your response to this is some tortured logic about how without a seatbelt you might fly out of the car or some shit like that you're missing the point entirely.
Obviously eating cheeseburgers should be illegal because you'll put a strain on the medical system when you get hypertension and heart disease.