This is like worrying about the sun going supernova after you've just discovered fire. Yes, eventually Earth will be reduced to a blackened cinder. And yes, if humans managed to live forever, there would be unforeseen (maybe bad) consequences.
If I get to live to 200, I still won't worry about it. If I get to live to 1,000, maybe I might start to think about it. Fortunately, by then, I will have had 1,000 years of experience to maybe come up with better answers than now.
Can you imagine the hubris of telling someone who has lived for 10,000 years that death is good because you can't think of what you'd do with that time?
Moreover no one is talking about making it impossible to die. No one is going to force you to live forever.
And that's the real problem for the nay-sayers. They know that they don't have to live forever if they don't want to. They just don't want other people to live forever. They want to live in a world where other people die.
I'm in favor of improving longevity, but sometimes there is something to be said for other people dying. Imagine a world where Stalin was still alive and would remain so approximately forever.
I don't think this is a reason to avoid research on aging, but immortal dictators could certainly be a downside.
> And that's the real problem for the nay-sayers. They know that they don't have to live forever if they don't want to. They just don't want other people to live forever. They want to live in a world where other people die.
If one can make a good argument that people living forever would have too many downsides in the long run, one might reasonably not want others to live forever. This is similar to environmental policies. Even though one may not live through most downsides of current bad environmental policies, one may still want good environmental policies for the sake of their children.