People should spend it on something that can make people happy. Make your friends happy. It's more fun that way and think about with money, how much plans with a friend someone can make.
There's also the kind of people that puts off what they really wanted for so long for something so cool that they just saw. That's a bad idea because not only are they getting caught up in the moment, but they might not spot the item's downside until they spend their hard-earned cash for it.
In the end, money doesn't make a person entirely happy and the only way spend money wisely, is to think wisely.