I found an interesting quote. I put it here, translated from German by myself:
So, capitalism never works out, because it constantly produces more than can be bought. That it can be maintained that long and produces a relative wealth for a small part of the human population is just because of perusing global differences and because of employing robbery and fraud. But even this wealth has its price and can only be seen as a relative wealth; because, one has to take into account the physical and mental degeneration and dissatisfaction of the wealthy citizens, in contrast to the often happy people of these plundered countries, even though they are often called “poor people”. [source]
Now what does this mean, it always produces more than people can buy? It works like this: the capitalists are those who, for any reason whatsoever, were able to accumulate some money. Now if they would use up that money for consumption, we would not have any problem, but: they do not want to lose that money again, they want it to make more money instead, to live from the interests (they are capitalists after all). So they invest it into companies (or states, which get it from companies by taxes), as this is the only way to “make gain”. Now if companies would spend all that money on their employees which again would spend it all on consumption, there would be no problem again. But the largest part of the money is spent for production technology, which then is used to produce goods for which there are no buyers. Because the employees did not get much …
In short: capitalism dies from deflation in the consumer class. Because too much money went into creating production facilties as a way to make more gain, neglecting that by cutting employee wages, they will (on large scale) lack the ability to consume. Making the production facilities run idle.
And shorter: capitalism dies because investing in production facilities is a bubble.
Addition: if we define consumption as an “irrevocable assignment of money to material goods”, then creating production facilities is of course production, too. But, if people cannot afford the goods, it is a form of consumption that does not increase the wealth in society, a useless assignement of money. Races around the moon would be just as useless.
Of course one could also argue that, if there is more supply than demand, then the prices will fall. Which would solve the problem if the capitalists would do that by waiving a part of their gain; but they always try to do it first by cutting employee wages. Which then reinforces the whole problem (on society scale).
After all, this leads to the following insight: an economy is healthy only the price sum of all consumer products produced and the sum of all employee wages is the same! Which is an objetive indicator for how much work time is worth: as much as needed to buy everything that is produced. The problem is, it seems that this condition will leave no gain at all to be made by capital investment! If somebody saved up capital, he or she might invest it as a tool (“lever”: allows to do move bigger things), but can not expect to make gain with the capital, but by using his / her own work time. The hourly wages of course can differ, and can make up the lack of capital interest (at least partially).
So as a solution, we would need this (and only this) element of a controlled economy: nobody is allowed to increase production capabilities (like founding another company, or optimizing current capabilities) if the wage sum of the whole society does not allow the society members to buy all the expected new products. This will make capitalists increase the wages of their employees to get allowed to found new enterprises. And that way, the employees get a fair share of the capitalists’ income (where fair means, enough to buy what gets produced).