The entire purpose of health insurance is spreading risk across a wide and diverse risk pool.

> why should I also be subsidizing Billy "video-games-are-my-exercise" fatass's chronic health conditions?"

Nobody is asking you to: enrolling in insurance is a choice in the USA.

Also, replace "chronic health conditions" with "unavoidable inherited genetic risk factors". We don't want Billy to be screwed for life just because he was born to a suboptimal combination of parents.