Why doesn’t happiness last too long?

Let’s imagine that one person won million dollars in the lottery. And another man was hit by a car. Who do you think will feel happier in a year?
As a rule, we are confident that good events will make us happy, and something bad will lead us into the abyss of depression. In fact, in six months or a year, the level of happiness will be approximately the same. A person gets used to everything – to both good and bad.
Harvard psychologist Dan Gilbert cites a lot of research: it doesn't matter whether we move to sunny California or the dark north, get married or lose love - the level of joy will eventually return to our usual "point of happiness."
This is called a psychological immune system, a mechanism for protecting our psyche from extreme influences. It helps us cope with grief and move on. But at the same time it muffles the joy of pleasant events.
As a rule, people do not know about this mechanism, therefore they do not take into account its effect. And this is convenient for marketers to use for selling expensive products. The seriousness of the costs helps them convince customers that after a purchase, literally the whole world around them will sparkle. Although in reality only that part of life will change, and that is not for sure, that is directly related to the purchase.
In reality, happiness cannot be bought. But since people don't think about the existence of a psychological immune system, happiness can be sold.