I haven't found many good sources on this, but it doesn't seem like many corporations these days need nearly as much investment capital as they possess. Do big corporations in America spend nearly as much as they receive in investment, or are they just holding onto a large amount of money for no reason? I found some links to an example for Apple Apparently, Apple holds 203 billion worth of cash in the form of investments Source but it seems that they spend less than 20 billion each year. Sources Additionally, Apple has never made less than 40 billion in income since 2011, and they made 89 billion in 2015 Source I imagine that, multiplied by hundreds and hundreds of corporations with similarly high stock market values, a lot of money is just sitting in the hands of these corporations who have no intention of spending that money. I'll change my mind if someone can provide a reputable source which proves that we aren't wasting a ton of money in our stock market system.
The stock market system results in wasteful amounts of capital being accumulated by corporations.