There is no reason to believe what rich people say about their own contributions to the economy, etc. There is an element of truth to their ideas, as there are to most.
What I would say though, is that we need rich people for the variety.
Variety is good. The binary mind secretly, perhaps, despises variety. The "blooming confusion" William James spoke of, is the source of originality and growth. The binary minds wants nothing so much as to sort, regardless of reality -- just get everything into this or that category. Problem is, these drawers are artificial.
We need variety. We need rich people.