There’s amusing statistics that show that if you’re out of shape and a smoker, you get a bigger bang for the buck from getting in shape first than quitting smoking. Disclaimer: not an endorsement of smoking.
There was a ted talk that said bicycle helmet laws would kill more people than save.
The reasoning was preventing people from riding would also prevent increased fitness, and more lives were lost from that than saved from accidents.
EDIT: I think this one: https://www.youtube.com/watch?v=07o-TASvIxY