I've said this before in other contexts, but it doesn't have to be a conscious decision or conspiracy.
A key concept from Physics that I wish was more widely understood by the populous at large is that of the "stable attractor". In chaotic systems you often get certain configurations which are locally stable, often highly stable, and they often attract more elements of the system into this configuration.
It's a common natural phenomenon responsible for much of what we see in nature.
In political and economic systems you often get stable attractors - systems which aren't specifically designed but where behaviors and interests align in ways that are mutually reinforcing. Sadly often with deleterious consequences.
Another way of looking at it is the Wisdom of Crowds viewpoint. Large groups of individuals making small individual decisions based on limited information have collective effects which can be seen as a computer, where regulations and restrictions on the decisions they can make become the programming. The more people making up the system the better the machine is in making collective decisions that achieve its goal.
The core program of our system is interest on capital. This underlies everything in our economic system. It's a simple concept but our markets are built around it, our government funding is built around it. Our lives, pensions, mortgages etc are built around it.
The machine that is our economy with such a large number of people it's very effective at returning interest on capital. As capital is owned by a dwindling percentage of people it's not surprising that this leads to a concentration of wealth. Basic arithmetic shows that in a system where all capital flows through a machine returning interest on capital it eventually becomes more and more concentrated in those who started out with the most capital. Without redistribution of wealth downwards through taxation and policies this is inevitable.
As the author says. Therefore decision making becomes more concentrated in the owners of most of the nation's capital.
Long story short this is an inevitable feature of the capitalist system. It's not a criticism of it per se. If you look at the advocates of capitalism from the beginning they've assumed that government and policy will place regulation and restriction to prevent the overconcentration of capital through this mechanism.
Unfortunately part of the stable attractor at work in the US is the confluence of money and politics. More than any other western nation the US political system is heavily influenced by money, and as a result once capital becomes sufficiently accumulated we get regulatory capture in the financial sector.
No conspiracy. The author doesn't suggest a conspiracy. Just a stable attractor. Which is in itself far more nefarious because it's far harder to remove from the equation.