We think that the more we have, the happier we will be. We never know what tomorrow might bring, so we collect and save as much as we can.
This means we need a lot of money, so we gradually start judging people by how much money they have. We start to realize that money solves most of our problems. You can even change people's minds, then surely you can buy happiness. So, you convince yourself that you need to make a lot of money so you don't miss out on success. And for you to make money, you need everyone else to spend their money. And so it goes.