Why? Because socialism is inevitable and the whole free market thing is nothing but a fantasy. There can be no real separation between capitalism and the state, government and civil society. The state is not a scaffolding from which capitalism breaks and becomes its own, self-sufficient thing. For 30 years, that theory/fantasy has dominated global economic policy (in the form of the Economic Structural Adjustment Program). Now the truth is out in the open, and the whole world can see that capitalism is impossible without state support—its infrastructure, its general intellect, and public resources.
It has been only an advantage to the rich to make a political program out of an idea that places the individual and not the social as the source of wealth. The GOP has no other message than that, and today it is a dead message. Socialism is really happening because there has never been anything else but this form of wealth production. If it was not there, if all you could you see was markets and bankers, this was because its very fact was obscured by neoliberal nonsense. All one had to do was look at, say, cotton subsidies in the US to see that even under Bush, even during the economic boom of the mid 00s, socialism was alive and well. Socialism must be seen as either a tool for a few or for many, and that is what it comes down to. It's not a matter of socialism and capitalism but a matter of privatized socialism of public socialism.
But not only Marx was right. We must also pass praise some to Joseph Schumpeter, a 20th century bourgeois economist who, though deeply disagreeing with Marx, saw that capitalism could not avoid becoming what it already was: socialism.