"People die of cancer and other diseases everyday, and you considered it selfish to want to live? What about the impact on loved ones like children or parents?"

Not dying due to cancer at 20 and living to be 400 years old isn't quite what i would consider in the same realm of justification, but your opinion might differs.

And this: " The damage is from pollution, not necessarily resource consumption in and itself. Yes, if the air is bad, we're going to die more of lung cancer. The solution is to build a society that value clean air, a stable climate, and a life support system(biosphere) that isn't steadily being destroyed as a byproduct of our consumption. "

Which is exactly my point in all of this: Are we there yet? not even close. Will people try to make living forever a reality regardless? i think so.