Falling life expectancy is a statistical fiction due to changing demographics. And health/medical outcomes are still better, most of the problem is systems that encourage people to die because they can’t afford care.
Responsibility doesn’t sum to 100%. If I fly on a crappy airline and get in a plane crash, it was partly my fault, and also the fault of pilots, maintenance people, regulators, executives, and many more. If someone makes a box with a hole in it labeled “free prize inside” which chops off your fingers, it’s mostly their fault. If everyone knows that opiates are addictive, and a pharmaceutical company says they figured out how to make non-addictive ones, and gets regulator approval, and convinces doctors to prescribe their new drug, and to tell patients it is not addictive, then I think lack of personal responsibility is only one small part of the problem.