The Knight's Tale - Parts 1 & 2

It seems people in Chaucer's time literally named "Fortune" the higher power that controls both gains and losses in life. Most people still believe in some version of this; however, we tend to think we have something to do with our good fortunes while we blame other people for our bad fortunes. This helps protect our egos. Are there any other reasons we might feel the need to attribute our gains and losses to anyone?