>If you accept an empirical view of the universe, no matter what you do, you will eventually die. Your experiences of the world will cease to exist. Therefore, the only rational investment would be in life extension technologies (SENS, advanced prosthesis, etc.).

By claiming that the only rational investment would be life extension, you're making the implicit assumption that your life and experiences are worth something (otherwise, why bother extending your life?). If we agree there, why are hedonistic pursuits that (arguably) increase the quality of your life, any less rational than investments that increase the quanitity of life?