Well if you consider my opinion seriously, I would regard "Capitalism" the cause of this widening gap. I faithfully follow and believe in the teachings of my religion, which says that "Interest" in any economy is the root cause of financial destruction of the society. Since "Capitalism" is an economic system based on "Interest", it can truly never bring the rich and the poor closer to each other. Its very nature is such that it increases the gap between the the wealthy and the ordinary people's ownerships.
How is "interest" the root cause of this problem? Very simple; "Interest" benefits the lenders and is a burden on the borrowers. The lenders are 99.99% of the times those who have enough savings / extra wealth to lend them to others. When "lenders" keep earning "Interest" and the borrowers keep paying it, the wealth actually moves from the borrower's hands into those of the lenders, and accumulates there. This eventually increases the wealth ownership gap between the lenders and the borrowers, or the poor and the rich.
So what should be the solution?
The best solution to this is increasing circulation of wealth in the economy. And this increase in circulation of wealth could be achieved by establishing an economic system "free of interest". Islam provides for such an economic system, when it declares different sources of revenue for the state, amongst which "interest" finds no place. So you should have a read on the different sources of revenue that Islam puts forth for smoothly running the economic system of the society, to learn how to decrease the wealth gap between the rich and the poor. The following may help a little in this regard;