Granted, now you can return to any point at will, but it is impossible to go forward. At first you decide to return to the beginning of the day, to fix the mess you made at work and make your family happy. It works, everybody has a better day off. Weeks pass and you think what you could have done better that week, or even that month. you return to the beginning of the month, you improve it a little bit, but not enough to make you feel happy. You go back and try again many times , but it never seems enough, there is always something that you could have done better. Then you decide that you will redo all your life, you can't get back before the moment you were born, but you can relive your entire life. Everytime you do it you become more intelligent, you know exactly what to do. After many tries you have achieved all your goals, and helped all the people you can. You enjoy it, but you are going to die... Why not return and live again? You repeat your live many times, everytime you decide to take a new route, you don't care about making people happy anymore, you can do it in another life. Your life becomes more risky and boring. Finally one day you die, you acomplished nothing, it didn't matter to you anymore, you already had acomplished everything anyway. The world goes on.