A major internal contradiction with capitalism is that it needs workers to also be consumers. While owners (and the system in general) constantly seek to drive down wages, they also seek to continue selling their products and services. The problem is that when workers have less expendable income (due to low or stagnating wages), they also have less buying power.
With the natural evolution of capitalism and the onset of globalization, American workers across the board have suffered immensely. Yet, consumerism still drives the American economy. The solution for this contradiction has been consumer credit. The typical worker now lives far beyond their means because that is how this contradiction plays out in real life: we all make less (in terms of real value), our wages and salaries stagnate, and costs of living continue to rise, but we're still called upon to shop, shop, and shop some more. This consumer activity is needed to fuel the economy.
There are problems that arise from this contradiction and its "solution." As credit usage follows the boom-bust, cyclical nature of capitalism, so does the inevitability of severe recessions and depressions. In all likelihood, much of the credit that is used to fuel "booms" simply cannot be paid back because wages naturally lag far behind costs.
We are entering another breaking point in this cycle. As of August of 2017, total consumer debt in the US hit $12.8 trillion. Auto-loan debt was $1.2 trillion; student loan debt was $1.3 trillion; mortgage debt $8.7 trillion; and credit card debt $784 billion. These numbers are at or near record highs, all previously achieved between 2007-09, the beginning of "The Great Recession." However, this time around brings an unprecedented factor with it:
Quantitative Easing (the Federal Reserve's large-scale purchasing of assets such as U.S. treasuries and government-supported mortgage-backed securities to stave off a complete collapse of the financial system from the '08 bust) has drastically increased the Fed's balance sheet, from just under $1 trillion (2008) to roughly $4.5 trillion (2017).
The Fed started selling off these assets (to reduce its balance sheet) in December. Doing so could very well cause interest rates to increase rapidly, leading to unwanted volatility in financial markets. This Fed activity coupled with current consumer debt levels brings us into unchartered territory. Naturally, the working class is doomed either way under capitalism. Nevertheless, be vigilant, fellow workers.