A very poor underprivileged person might think that it would be wonderful to have an automobile or television set, and should he acquire them, at the beginning would feel very happy.
Now if such happiness were something permanent, it would remain forever. But it does not, it goes. After a few months he wants to change the models. The old ones, the same objects, now cause dissatisfaction. This is the nature of change.
Photo source: marble caves (Patagonia, Chile)