Imagine being instantly teleported into an advanced alien spaceship that's stationing in earth’s orbit. You’re brought in front of the heavily armed ship’s commander. He gives you a choice between life or death. If you decide to live, they’ll exterminate all other human life in an instant. If you choose death, humankind will stay untouched. For the sake of argument, you can be certain that’s what will happen. Likewise, you’ve to presuppose that it’s certain that there’s no post-life after your death. By dying you stop existing as a conscious being. Forever.
There’s no other way around. You’ve to make your choice. Which one would you choose? Which decision is the most rational?
Imagine you choose death. There’s one certainty about this path. Your existence will stop being. Your existence is the base for all your values, memories and thoughts. Without it all those things mean nothing. You can experience things only because you exist. By killing yourself, all your values will stop existing with yourself because they’re rooted in yourself. The people you love, your dreams for the future, your past experiences… They may still exist outside of your existence in a physical world, but it won’t matter since there’s no “you” to give them meaning.
Now if you go for life. There’s a good probability that you’ll live a miserable life, but you can’t be sure that it’ll always be the case. There is an undefined number of ways to sort yourself out alone in the world. Or the aliens may even bring you to their home. If you fail to get out of that sad life, you’ll always have the choice to terminate your existence whenever you want to.
After thinking about this, would you still make the same decision?