Yes, jerking off in a park and having an HIV partner can lead to death. (facepalm)
Anyway, lifestyle and by that I mean a past history of drug use and smoking can lead to premature death. It may have caused his heart failure, directly or indirectly.
Unfortunately, drug addictions aren't as simple to kick as some people on this board seem to think. And when you have a virtually unlimited supply of money, it makes it almost impossible.
Toxicology reports will be released, then we'll know for sure.
Either way, very sad. RIP
http://www.telegraph.co.uk/news/2016/12/26/george-michael-died-alone-boyfriend-reveals-battled-secret-heroin/