No irony at all. Tobacco is the biggest killer, about 5X alcohol, and alcohol is about 10X illicit drugs. On top of that, illicit drug deaths could be brought down by taking the prison and police resources used in the Drug War and using them for harm reduction. Another thing about the Drug War is that zero deaths result from marijuana, and that's still a big component of the Drug War.

On the other hand, guns are used in about 2/3rd of suicides.

"guns are used in about 2/3rd of suicides" - correlation does not imply causation, it is especially clear in this case

Yeah, but which drugs? There is no laxity for meth, crack or pain killers, which I would assume account for these deaths--not marijuana.

Alcohol is probably included in these deaths.

Maybe one day we'll extend natural life expectancy so far that suicide and drugs are the primary causes of death?

Is immortality the presumed goal?

Immortality is always the goal. You can't have a goal without having time with which to achieve it. Assuming you never stop wanting to have goals, you should never want to die. Given that death is something people tend to accept rather than wish for, almost everyone wants to be immortal.