Yes and no. They also use it to buy and store commodities, in the believe that money will devalue and it is better to store it as gold or similar. This line of thinking pretty much creates no value - the money does get kept in a underground vault, albeit rarely in the shape of a swimming pool.

Where any investment happens also matters - I suspect that recently most of the value of investments have gone to raising the quality of living conditions for the middle classes in China and India, rather than in America or Western Europe. In a sense, the planting is being done overseas, and the harvesting is happening at home. One may argue that this is morally desirable, but it's not clear that it is the outcome that would be chosen by enlightened American or European self-interest.

Interest rates being as low as they are also seems to imply that there are few solid value-creating investments to be had at home in a retail sense - otherwise it would be trivial to invest money at a higher rate of interest and become quickly more rich.

One final point - money is power. When money is so heavily concentrated in the hands of very few people, you have the same very few people being very powerful economically and picking winners and losers. This happens to be exactly the problem that a lot of people who are for market-driven economies have with socialism/communism - power concentrated is too prone to failure and not as great a driver for progress as power diluted.