Few of us can accurately gauge how we will feel tomorrow or next week. That's why when you go to the supermarket on an empty stomach, you'll buy too much, and if you shop after a big meal, you'll buy too little.
I actually think the same things do make most people happy. The differences are extremely small, and around the margins. You like peach ice cream; I like strawberry ice cream. Both of us like ice cream much better than a smack on the head with two-by-four.
The mistakes we make when we try to imagine our personal futures are also lawful, regular, and systematic. They, too, have a pattern that tells us about the powers and limits of foresight in much the same way that optical illusions tell us about the powers and limits of eyesight.
Your emotions are meant to fluctuate, just like your blood pressure is meant to fluctuate. It's a system that's supposed to move back and forth, between happy and unhappy. That's how the system guides you through the world.
Part of us believes the new car is better because it lasts longer. But, in fact, that's the worst thing about the new car. It will stay around to disappoint you, whereas a trip to Europe is over. It evaporates. It has the good sense to go away, and you are left with nothing but a wonderful memory.
No one likes to be criticized, of course, but if the things we successfully strive for do not make our future selves happy, or if the things we unsuccessfully avoid do, then it seems reasonable (if somewhat ungracious) for them to cast a disparaging glance backward and wonder what the hell we were thinking.