Yes, it's a synopsis of a lot of stories. But I feel obliged to point out that, in real life, I know a number of people in quest of immortality who lead quite awesome lives on a day-to-day basis, because the same style of rationality and nonconformity that leads you to seek world optimization and indefinite life extension also leads you to, say, polyamory.

I also know some sad people in quest of immortality, but they were generally sad before they found out about that stuff. In general, I think that seeking immortality has surprisingly little effect on your prior personality. It's just something you do if you have enough of a logical frame of mind to think "Life is good, death is bad, and Voldemort isn't a real person", but the logical mind is the cause, not the effect.