What really motivates donors?

From the study presented in this blog post, it seems that donation is a form of repayment for something one has received in the past.

I wonder if people are interested in donating for a repayment that will occur in the future. We can all afford to make donations when we are in a good economic conditions. 

But what if we could save money for harder times by doing donations?  

What if I can be repaid for my donations when I really need it?