One huge problem with your statement is that the reality of our futures does not depend on what we believe. It is what it actually is. I bought into their promise but then realized it isn't true.
You can say I don't know what the future after death is. For an absolute certainty, I cannot prove that I do know it. But we live and we die, we exist no more. If that is wrong, then some megalomaniac demanding my licking his boots during this life to grant me part of that afterlife while he is practicing his high level neglect of mankind, it's just not worth it to me.
I am assuming this life is it, though I hope for more. I was talking about those who if eternal life was possible (not limited to jw or religions version but any) but those who say they wouldn't want it. I think it's a shame we weren't born further into the future. If we truly are alone and everything happened by chance, and how rapid science is advancing, at some point I think extended life if not eternal life can be discovered.