How much do you think pooling risk disincentivizes people from exercising or eating healthy? It's probably not a lot because the U.S. is one of the most unhealthy and least insured places in the West.
That cookie addict will be paying for your medicare and social security for 30 years, while you pay for their medicare and social security for 5.
Everyone dies, and healthy people live a long time, and can die very die slowly and expensively. He'll pay for your full time assisted living while you die from Alzheimer's at 95, you'll pay for some critical care after his heart attack at 65.