I think it’s a bit of a stretch to say people are unhealthy because insurance is cheaper. The average person does not live in a way they want to harm themselves.

I would say it’s because most Americans don’t walk or bike much, food desserts are plenty, transit infrastructure sucks, overworking, and lack of time for vacation/self-care all contribute.

You are forced to have a job if you expect typical medical coverage, and making people do something they don’t want to do won’t incentivize them to take care of their health.