Because men receive worse medical treatment. Just compare how prostate and breast cancer are promoted. It also corresponds with other statistics like life expectancy, medical expenses, disposable income...
Men were significant less likely to be taken serious and admitted. However those few who are admitted are then taken more serious, and get more direct treatment than women. From a cultural perspective, men are viewed as always healthy, and in the exceptional case where its proven false then they are expected to be restored back to the norm. Women get the opposite cultural treatment, where they are easy accepted as sick but then the health system gives up and don't expect them to be able to be restored back.
What about an alternative... Men are less likely to seek medical treatment?
Yet I have had male colleagues laugh/take the piss out of me for going to the doctor. Yet I think I am the only male in the office who doesn't have some kind of chronic (or close to it) condition at 32. It seems everyone at work has back pain or some other chronic pain because they ignored it when it could have been solved easily. Now some of them need surgery for trapped nerves or slipped discs but don't treat it still! Stupidity IMHO.
The worst I know of is a guy I used to work with lost his testicles because he ignored pain and a lump which was cancer! He is lucky to still be alive.
Girls often don't want to become programmers, and, as I know it, we don't say "It's their fault". We just raise the issue and everyone is fighting to make them want to become programmers.
It's way past time we apply the same reasoning to men's problems as women's problems. Males not seeking medical treatment could be because they're not aware of it (i.e. not enough funding for male diseases as female preventive programs). Or it could be because males are more suicidal about life, because they get the short end of the stick in pretty much all countries, despite the way it is framed in statistics, and we should equally fight for that. In any case, any statistics which leads to 6-year-shorter life expectancy denotes a very acute problem, for which funding should be given in equal level as for women's equality.
I made no attribution of fault... simply an alternative primary cause to the person I responded to.