Critics of the current system will argue that people are taught to be selfish by our society. Partly because most of the institutions you need to interact with (such as banks, your job, the government, shops etc.) require you learn to account this way. But there are many informal parts of your life : within your family, within your networks of friends, within your department at work, and within institutions like churches, sports clubs, parent's associations and volunteer projects, which avoid such rigid accounting. As long as you are roughly perceived as "pulling your weight", you'll be accepted in these communities on a gift basis.
How much difference is there between conspicuous consumption and PotLatch or conspicuous donation. Both involve spending resources on things you don't need, mainly to satisfy a psychological motivation. Why should we think one is human nature and the other not?