The lack of social mobility and the skyrocketting relative inequalities is a huge problem, but people often misinterpret what "the poor gets poorer" means.
Compare the life of a poor family from the 1970's and the same poor family in 2010. Only one has easy access to a washing machine, has a TV and a computer, can save up for short vacations... the other doesn't.
I do not believe money grants political power as much as some may think but I would like more effort being done to make sure it doesn't, and I don't see that happening any time soon. Another problem is that in some economic sectors, businesses naturally regroup in big structures, which can become defacto authorities in their field, or become so big that the whole society can't let them down even though they are run for individual profit.