That's just an opinion, formed over centuries of humans trying to make peace with their mortality, because they believed it was inevitable. There's no inherent truth to your words; it's just a philosophy.

I'm not really afraid of dying, per se, but as a sci-fi buff, I am deeply sad that there are amazing technological advancements that I will never get to see. Even if the world 300 years from now (assuming humans still exist by then) looks nothing like what any sci-fi author could have envisioned, it still bums me out that I won't get to see what that ends up being like. (And yes, I've considered the possibility that things could be much much worse than now in 300 years, at least for humans.) My only worry about this is that if I were "asleep" for 300 years, that "stranger in a strange land" bit could be very real, and I don't know that humans are well-equipped psychologically to deal with that kind of... dislocation.

I'm not religious, and don't believe in an afterlife, reincarnation, or of anything after we die. So if I want to see the future, in any shape or form, life extension is the only way. I doubt medicine will solve aging and mortality in my lifetime, so even a moonshot like cryonics would likely be my only hope -- even such a remote hope -- of seeing the future. Not sure I'd actually go for it, though, but I get the appeal.