Plenty of normal men die of heart attacks by 65 y/o.
Unless he comes from a family that dies young, it’s likely the lifestyle he led contributed to an early death.
I’m not saying absolutely that it is drug-related, but extensive drug use and being in the entertainment industry do go together.
In my opinion, being on the road for 200 nights/year, or more, has a lot to do with why he died so relatively young.