No one considers the downside of being immortal. Everyone fears death so much that they think living forever is a great thing. Not having to worry about that whole death issue does have its advantages, sure, but there is always plenty of yang to go along with the everlasting ying.
No one considers that immortality means you have to put up with the shit of this world not just for a lifetime, but for a thousand lifetimes. They say, "But you never have to step over, into, you know, the unknown." But they never realize how utterly boring knowing so much can be. A little trip into the ether, a spiritually permanent move as it were, would be quite welcome in my life at this point.
No one considers that immortality means you have to put up with the shit in yourself not just for a lifetime, but for a million lifetimes. They say, "Self-improvement--you can perfect yourself, learn how to adeptly maneuver this world..." But they never realize that nature/nurture isn't either/or, it's and. And nobody understands how much, how disgustingly much, nature there is in a man.
They say you can become rich, live comfortably forever. They don't realize how the novelty of everything wears off, and how novelty itself becomes less and less satisfying. They don't realize how hard it is to manage an estate for a lifetime when for everyone else it's a lifetime and for you it is a day. Your accountant was younger (looking) than you when you first hired him, and he did a stand-up job. But now he's got a piss-bag attached to his walker and you don't look a day over 30. No one realizes it is a nearly impossible scam to "die" and leave money to yourself when you look exactly the same as you did 80 goddamn years ago. No one realizes that it looks mighty odd on the government records if somebody doesn't die in, say, under 150 years. You get a letter from the goddamn president when you hit 100 for Christ's sakes.