I assume you mean that dying is the most terrifying pat of the natural human experience. Also, I'm not sure why you infer that me thinking death is a natural part of life, means that I'm happy or eager to die.
There are many reasons that people living forever would be a problem for society, the most obvious being an ever-increasing population.
Also things like chronic disease and violence are a "natural" part of life but we seek to minimize or eliminate them, why do we have to accept a "natural" death and not attempt to put it off as long as possible?
> the most obvious being an ever-increasing population
This notion seems to be commonly accepted as bad without being properly examined.
Why is a larger population in and of itself a problem? Lots of societies throughout history have used less resources than we have and we have superior tech now. We are well within our abilities to use the same or less resources with a much larger population. Why should there be a limit based solely on undefined notions of "too many"?
Fertility rates are below replacement, which means that population sizes are convergent. A decreasing population is a more likely future scenario for many western countries, even if human lifespan was indefinite.
Fertility rates are currently below replacement, there's no good reason to imagine they will always be that way, particularly after global population numbers peak and fall to, say, half or a quarter of their peak.
What's the basis for your claim? You seem to be saying that people are magically going to have more children because there is a desperate need for them? Maybe if government finances this but how will that work economically at such a huge scale? Will children be born in debt for their birth?
There are many reasons that people living forever would be a problem for society, the most obvious being an ever-increasing population.