It isn't that anyone should live forever. It's the fact that cancer is such a painful death. It is painful both during the process of it taking over(attacking/destroying) the bones and organs of the body as well as the final moments of it causing organs to slowly shut down. For example have you ever seen a person die of lung cancer? It is a very painful process. I watched someone go thru it firsthand and I certainly hope I do not go thru it - a ton of extended pain, even when the pain was 'managed' thru Morphine. If taking the argument that no one should live forever, then I assume you would support that no one should never go to a doctor .. starting off with the birthing process and leave it all to chance for the unborn and mother.
If I'd been around 12,000 years ago to invest a few bucks, and it grew at a 2% APY since then, I would currently have enough money to end poverty and global warming, while mining the asteroid belt to build an Orion-class starship in orbit.
Why are you in favor of poverty and global warming, and against asteroid mining and starships? There's so much more you can do while you're alive than you can do while you're dead; and attempting to extend your time alive does not preclude enjoying it.
I applaud the fact that that's all you responded to, given the parent said it'd be stupid to cure polio and better to let poor people die to reduce overcrowding.
It isn't that they die - it is that they die before they can realize many of their dreams, before they can change the world in the way they have been working towards, before they're done.
We hate cancer because it takes from us those who wish to give so much without consideration. An indiscriminate killer that wastes our treasures away before our eyes, leaving us with only memories, partially realized dreams and the rage of "why now, when there was so much more good to be done?!"
I think that the comment was more about death by cancer than death itself. Cancer can happen at any moment in your life, and some types can occur without any apparent cause that we can determine(aside from twiddled bits in our DNA). When it happens, our own bodies rebel against us. Death by cancer can be long and extremely painful for the person dying as well as loved ones. Death is always difficult for the living to cope with, but it is a part of life as you mention. I think that a 'graceful death', one that occurs quickly/painlessly after a long life well-lived, is not a bad thing to want.
The person you've responded to never said we should live forever, nor did they say they hate the fact that people die; rather, they said they hated cancer. That's an important nuance you left out from assertion, isn't it?
Sure, you may not want people to live forever, but that has absolutely nothing to do with the above comment; indeed, what you've said might be viewed as somewhat callous when considering the context that someone has revealed that they have terminal cancer.
Ultimately I think people are more annoyed that they don't get to choose to hang on as long as they'd like. Sure its a bummer, but for gods sake be grateful for any time you do get.