Salu, are you sure you are a doctor and not a market researcher?
I would say heart diesase, in my early 60s. I am still very overweight (although i'm working to change that, lost 3 stone so far).
If you ask my bird, she's say car accident though
Although, doesn't sound like a bad idea. Being 80+ and:
1. defecating in your own pants because you can't get to the toilet in time
2. eating tins of expired cat food because you can't afford anything better
3. not meeting anyone because noone cares or everyone who does is dead, or you are too senile to hold a conversation with
4. living in a s**thole because you can't look after yourself
5. not being able to see/talk to anyone because you are blind or deaf
... etc. is not really living is it? Its just being alive for the sake of it. I'd rather top myself than go through that, living for the sake of it. Of course its not like that for all old people, but for quite a few it is. Seeing what some people have to go through, i'd rather top myself in a blaze of glory at least while I am still physically able to.