With so many millionaires and billionaires in the US and world how ..?

How is it possible that so many have nothing and so many have way too much? Why is it that those who have so much more then they would need in 3 lifetimes wont share with those who have not enough even for a day? I am completely confused by all the talk of recession and depression why there are those with 7 cars..3 homes.. 2 boats..and thousands of clothing in their wardrobe. How is it possible that we are suffering so much in our economy and rich folks don't all decide to open their wallets and share some of their excess. It's too much for me to understand!!