The reason for this is that we get to live and re-live the joy of experiences through memories and photographs. Buying an expensive TV or even a new car gives a momentary spike in good feelings that lasts for a few days. If something happens to them, they have almost become disposable – a sort of planned obsolescence. You go out and buy new. But when you take an amazing trip, you get the memories and the good time together — and every time you think of that trip, or you see something that reminds you of it, a smell of a scent that was in the air wherever you were, or you look at the picture on your wallpaper, your brain registers those joyful times and releases mood-enhancing endorphins that make you feel like you’re re-living the happiness of the experience itself. It stays with you, and you get to access it whenever you want.