Marx and Engels, observing the plight of the working class, opined that capital is a social good, and should thus be controlled not by the few but by the many. They railed against the capital-accumulation philosophy of the Western world, and proposed that neoclassical thought was the best friend of individual wealth and the worst enemy of families, civil liberties, and the average person. "The bourgeois claptrap about the family and education, about the hallowed correlation of parents and child, becomes all the more disgusting, the more, by the action of Modern Industry, all the family ties among the proletarians are torn asunder, and their children are transformed into simple articles of commerce and instruments of labor." (Karl Marx and Frederick Engels, Manifesto of the Communist Party, 1848) And, "In proportion as the bourgeoisie, i.e., capital, is developed, in the same proportion is the proletariat, the modern working class, developed -- a class of laborers, who live only so long as they find work, and who find work only so long as their labor increases capital."
While most of Marx's criticisms of the capitalist system are quite valid-indeed most anti-Marx polemics have not addressed his criticisms specifically, but focus instead on his solution-it is clear that he was unable to provide either a cohesive argument to explain why Capitalism might be unstable or why his solution is a viable alternative. Communism and Socialism in all their flavors have proven to be self-destructing political-economic systems, breeding the very instability Marx predicted for Capitalist markets.
If we judge a tree by its fruits, then by most counts applied Marxism has come out as poorly as or worse than capitalism. Marx dreamed not of a quasi-anarchy, but more of a form of closely regulated democracy. He specifically called for a dictatorship of the proletariat, instead of espousing a general opposition to rulers. Marx saw that child labor is an obvious consequence of unregulated markets, and that marriages and families become more economic than humanistic. Marx saw that those with superior leverage and starting positions in the race would win unfairly and usually in deterministic fashion. His mistakes were primarily not in his criticisms and observations, but in his analysis and proposals. Marx could never really show why the capitalist system would be unstable. Has it turned out to be? Quite clearly not. There may be many reasons for this, but in any case, the proletariat have not risen up to overthrow the capitalists. Instead, many actually support the capitalists vehemently, subscribing wholeheartedly to the propaganda of those that purportedly oppress them (think of middle class, card carrying Republicans in the U.S.). As to Marx's solution to the capitalist problem, the results are even clearer.
Marx was wrong about communism. It is a completely invalid, imploding solution to the problems he saw in capitalism. Mostly, Marx forgot some basic principles of humanity that have shown themselves anyway in the Russian, Cuban and Chinese systems, the most important of which is that power corrupts. Perhaps the reality is that corruption is inherent even without power, but power enables individuals to freely express that corruption. In either case, there can be no system of government whose purpose is not to perpetuate itself and gain power, because the moment that government is threatened by greedier forces, it will buckle under the pressure. Might makes right. How many times have we seen the powerful get away literally with murder, while the ghetto-dweller is hunted down for any deviation from the law? Stories of petty criminals and their accomplices receiving impressively, disproportionately large prison terms abound, while the perjuring President of the United States pardons financiers convicted of major swindling and tax evasion activities. Around the world, who is responsible for more death, destruction, rape, robbery, etc.: the poor or the rich? And yet, Marx's solution cannot work. The moment a well-intentioned proletariat revolts (assuming it revolts at all), a less democratic force intervenes and steals power away from the whole people in favor of a few individuals. This happens so regularly, it may almost be said that people don't especially mind being ruled and exploited.
The question deserves some further pondering: why don't the proletariat revolt? With such a huge percentage of the world's wealth in the hands of so few, why isn't it easy to turn the tables by sheer numbers and spread things around more evenly? Why, in fact, do the masses of have-nots not decide to end the first game, congratulate the winners, and set up a new game with different rules? Is this the result of some evolutionary development, leading to a cowering, highly individualistic agglomeration of humans with no motivations other than convenience and laziness? The answers to these questions are obviously not simple, nor are they mostly known. However, a look at Institutionalist Theory should help at least a little.