Simple. Wealth is a destabilizing event. Increases in social affluence increase instability in a society, and invite schemes that procure wealth through trickery and force as strongly as they do those that involve creativity and labor. Indeed, the former is significantly easier than the latter; in a tip of my hat to the anarchists, we accept the existance of a protection racket (the state) to hopefully ward off the greater evil of unmanaged protection racket schemes (what is commonly called 'anarchy' by non-anarchists and 'nihilists' by the utopian true-believers).
People make wealth, in a system that promises to protect a portion of that sum for the makers in return for a cut. The state gaurantees security, and this wealth rises exponentially. There arises a 'class' that learns to exploit this desire for security, which tries to extort wealth from the system by arming those without it. This is done by the Left in the form of rhetoric (that justifies and ennobles theft) and more direct means (by providing for the 'armed' part in 'armed struggle'). For the longest time, Russian communists and their left-wing apologists talked a peace storm, while doing their energetic best to ensure that their henchmen around the world did not want for firepower. Has Jennifer Casalo been so quickly forgotten? Were Jesuit priests burying weapons in churchyards in the name of peace? Please.
The simple fact is that, for those outside of the system that provides for the bonanza of material abundance made possible by the industrial revolution, 'armed struggle' can be quite a lucrative enterprise. This sort of thing goes far to explain the actions of a certain group of Rwandans recently, vis a vis a group of hapless tourists on Safari in Kenya.
It is my impression that as many people as possible should be brought into the capitalist system, so that they might thereby have a claim to the wealth that inevitably will be had by them through simple numbers and force of arms. This, however, is a debate best conducted amongst conservatives and loyalists to civil society, as the motives of those on the Left border on sheer personal parasitism. Or so my impression stands, at the moment.