Piketty's book describes this phenomenon as well - his book is fundamentally about the world moving from a situation of having a $1M factory producing $100k in income to a situation of a $2M factory producing $150k in income. (I.e., r=2, g=1.5.)
Elon is one of the very few people who put their money to excellent use.
But for every Elon Musk out there, there are hundreds of Paris Hiltons.
Had she kept her inherited wealth it would be mostly in the form of hotels rather than money.
The people to look at are, say, Peter Oppenheimer, former CFO of Apple (picked at random). I'm sure his net worth is in the hundreds of millions and he has a few very nice houses -- but what's the likelihood that a significant portion of his wealth is reintroduced into the economy? I really know nothing about him, so maybe I'm being unfair and he spends lavishly on yachts and mansions, or is an angel investor in 100s of startups, but I think the prototypical Fortune 500 C-level is probably someone who lives very well, but not lavishly and not up to their very generous means.
I should also note I'm excluding passive investment in mutual or hedge funds for the sake of argument, but I'm not sure whether they produce sufficient results to count as "reintroducing" money into the market.
As an owner of shares of SPY, he then owns small percentages of factories, airplanes, hotels, logistics and similar things. Virtually no one is actually sitting on money because that's a really dumb thing to do. Investing in productive capacity just provides a lot more money.
I think the problem pointed out by the original article is that they don't like this because it tends to produce oligopolies (i.e., "chains"). Unfortunately, I think that's just because non-colluding oligopolies are efficient.
So the market is "working," some just don't like the outcome.
If one happens to invest into the inefficient company in a long term it is going to be bust along with investor.
How comes this is not productive?
I own shares of SPY, if I sell them to you what exactly changes?
Take away the market and the company wouldn't get any money.
Beyond a certain limit, ownership is bullshit. It's really stewardship, but it's forgotten its true limits and purpose.
When you're touching so many people and resources, you're a steward, not an owner, period. What's lacking now is a mechanism for the bad stewards to undergo corrective action.
If you believe Piketty that the wealthy are better investors than the rest of us then the wealthy are actually doing useful work: directing resources towards their most productive use.