OP seems to be suggesting that a key to living a long life, eating healthy, exercising staying fit, being emotionally stable, may not necessarily lead to a long and worthwhile life so why bother? And then he cherry picks cases that fit that result.
Well that is sometimes true while it is also true those supposed negative behaviors have in many cases led to premature health and emotional issues. Like with many variable human things, its a Bell Curve with some people for a list of facets like genetics inevitably results in rapid aging by middle age while others smoking and drinking their whole lives reach old ages.
But a wiser way to look at such statistics is to understand the majority at the mean top of the curve will be affected by healthy lifestyles resulting in not only longer lives but more capable and enjoyable lives once they reach senior years. And today there is plenty of science based evidence to support more likely negative health if one say smokes cigarettes or is obese. Others will by personal choice they are welcome to, living Fast, Dying young.