A food seller cares about selling his food. The shareholders in a food selling company only care about getting profit from the company. This means that all the company cares about is selling as much of its food as possible, for the best price possible.
The shareholders, employees, farmers, etc. of the food company only find useful 50 million people. So what? Those 50 million people will find the other 50 million people useful in some manner. Money circulates, it does not make one transfer and then stop. Everybody needs something, and the 50 million people can't get the necessary services and products from the food company, it's too busy providing food. Even doctors go to other doctors when they're sick.
The shareholders, employees, farmers, etc. of the food company only find useful 50 million people. So what? Those 50 million people will find the other 50 million people useful in some manner. Money circulates, it does not make one transfer and then stop. Everybody needs something, and the 50 million people can't get the necessary services and products from the food company, it's too busy providing food. Even doctors go to other doctors when they're sick.
The point that you've missed is that the company that gets to the stage where it owns a market completely has no reason to sell 100M @ $2 if it has the power to sell 50M @ $10 over two years. If only 50M are sold into the market, and they're consumed, and it's a food monopoly, 50M have no way of buying that food. Only 1 arable land owner on the planet. The people cannot eat money, no matter how much they have.
This is still off topic, because this problem is irrelevant to how much money those people have.
Only one arable land owner on the planet is never going to happen in real life. So, that has to be assumed, for this model to work. But even assuming that, Why would they sell half their production? Why sell 50M @ $10 per year when they can sell 100M @ $10? The answer, of course, is that no sane monopolist would intentionally limit his profits when the idea behind monopoly is to maximize profits. If the people have the money, they can get the food. You're arguing that first, an impossible situation would arise, and then, that the person able to benefit from that impossible situation would choose not to. And why he chooses not to, that's the best part. You claim it is out of greed.