I believe that there is a universal law of compensation. You get what you give. You help somebody - then some time in the future somebody will help you. This "universal law" is what makes open source work.
I think it's more like you give what you get. Especially in the case of open source. Altruistic trends are kickstarted by idealistic or exceptionally kind souls, and then many people join in inspired by the example, or sometimes just conforming to expectations.
