Marx's argument for the inevitability of extreme wealth disparity and at some point a breakdown in the capitalist system is too long to put here, but I can summarize it somewhat. A worker is creating wealth - why else would a company employ him? Let us say he works as a carpenter for a furniture store. He takes $800 worth of wood, nails etc. every day and through his labor makes it into $1000 worth of desks, cabinets etc. What happens with that $1000 in sales? $800 of it goes to buying wood, nails, hammers etc. for the next day. $200 is left over. Some goes to wages to the worker who created the wealth, some goes to profit to the company owners. Let's say it is split down the middle, $100 each way. If the worker works 10 hours a day, he is creating $20 in worth an hour, but only keeping $10 of that. Or you could say he spends the first five hours a day working for himself, and the next five hours he receives none of his own wealth creation, it is expropriated by the capitalists.

What do the capitalists do with their profit? They invest! They buy more capital. They buy capital equipment so that twice as many cabinets and desks can be manufactured in an hour then before. Now, minus the capital cost, with $2000 worth of desks being made a day, with $1600 of daily costs on materials, and keeping the worker at a wage of $100, the capitalist is making $300 a day once his profits pay off the cost of the capital equipment. So the capital spending means a flood of new commodities.

The question becomes - who buys these new commodities? The worker is not going to be buying more desks - he is not making any more than he did before. So then you have "over-production" - too much over-competition, which is not good for capitalists. Marx believed this, but it is not a notion exclusive to Marx - GE CEO Jack Welch has talked about this, as has Peter Thiel, and others. So you get a situation where it is perceived there is a demand for cloud services - so EC2, Linode, Rackspace etc. fund massive capital funding and get into a price war with each other, and people can buy more and more for less and less. There is a ton of capital out there, and demand is not outrageous, so this happens. The bottom line though is the process of profit to capital to more commodities to more profit to more capital to more commodities can't be endless, especially with the consumers wages stagnating. You can get him to get into credit card debt and home mortgage debt and then pass laws saying he can't get out of certain debt and so forth, but this only kicks the can down the road, and makes the inevitable crash worse.

This in a nutshell is one of Marx's major arguments. It is in a nutshell - he wrote more than three large books on this which are difficult to summarize. Replying to thread to argue with one of Marx's ideas is fine, replying to this post because you found some hole in my incredibly condensed argument would be silly - I'm leaving out dozens of caveats which leaves massive holes in my condensed explanation. I have to leave out those caveats or else I'd have to write tens of thousands of more words.

These are interesting articles, especially the 2008 Marxist interpretation of the financial crisis -

http://monthlyreview.org/2013/03/01/class-war-and-labors-dec...

http://monthlyreview.org/2008/12/01/financial-implosion-and-...

Even if you disagree with the analysis, the data they point to is, I think, interesting. Liberals and moderates talk about wealth inequality, debt, how finance is dominating the real economy etc. They don't talk about the slowdown in real GDP growth, the decline of industrial capacity utilization etc.