What people profess and what people believe can differ wildly. Right now, most people don't see any obvious route towards living forever, and haven't even given that idea much thought; furthermore, most people likely don't see any benefit to their personally professing a belief otherwise, and professing such a belief goes contrary to social norms. On the other hand, many people gain (perceived or actual) social benefits from professing various religious, quasi-religious/spiritual, or otherwise socially acceptable beliefs regarding death. Combine that with the usual fear of any change to the status quo, and you end up with a society of people that by and large professes a desire to be dead at some distant point in the future.

On the other hand, if you had a practical implementation of immortality, today, with no major drawbacks, what subset of the population would actually refuse? I suspect far fewer people would profess a desire to die at that point.