Acquiring new possessions makes you happy—albeit temporarily—before your happiness level goes back to baseline. This means, you can keep purchasing new things to fuel your happiness if you have the means to do so.
As time goes by, however, you will begin to notice your piling possessions. Your possessions start to own you.
After all the spendings, your happiness is short-lived and now you need to spend more time disposing of unused items and sort your belongings. Things that made you happy then make you unhappy now.
Relying on making purchases to keep you happy is perversely counter-intuitive. But, we all know how overpowering the temptations to buy are.