Everyone should be concerned - right, left and every 1 in between.

[Fantastic Anarchist]

36. Some of his ideas, like scientific socialism ... (Edited)

... actually originated with the anarchist, Pierre-Joseph Proudhon. Marx admired Proudhon and formulated his brand after reading Proudhon's work, "What is Property?" The common misconception is that Engels formulated the idea, which is not true. Of course, once the relationship between Marx and Proudhon became acrimonious, then Marx started to treat everything he learned as his own, and dismissing those elements that didn't fit with his dogma in his revisions.

Edit:

Suffice to say, the accounts of Marx and Engels are highly distorted and almost always charged with scorn.[18] This is unsurprising given that they considered Proudhon as their main theoretical competitor within the socialist movement. Indeed, at the start of the Franco-Prussian war Marx wrote that the French needed “a good hiding” and that a German victory would “shift the centre of gravity of West European labour movements from France to Germany” which would “mean the predominance of our theory over Proudhon’s.”[19]

Be that as it may, and regardless of the misrepresentations that Marx inflicted on Proudhon, it is also fair to say that he developed many of the themes he appropriated from Proudhon (“One of Marx’s most important teachers and the one who laid the foundations for his subsequent development.”[20]). As Marx suggested:

Proudhon’s treatise Qu’est-ce que la propriété? is the criticism of political economy from the standpoint of political economy... Proudhon’s treatise will therefore be scientifically superseded by a criticism of political economy, including Proudhon’s conception of political economy. This work became possible only owing to the work of Proudhon himself.[21]

...

The awkward fact is that many key aspects of Marxism were first suggested by Proudhon. For Benjamin Tucker “the tendency and consequences of capitalistic production... were demonstrated to the world time and time again during the twenty years preceding the publication of ‘Das Kapital’” by Proudhon, as were “the historical persistence of class struggles in successive manifestations.” “Call Marx, then, the father of State socialism, if you will,” Tucker argued, “but we dispute his paternity of the general principles of economy on which all schools of socialism agree.”[22] Moreover “Proudhon propounded and proved [the theory of surplus value] long before Marx advanced it.”[23]

...

Marx argued that credit system presents “the means for the gradual extension of co-operative enterprises on a more or less national scale” and so the “development of credit” has “the latent abolition of capital ownership contained within it.” It “constitutes the form of transition to a new mode of production” and “there can be no doubt that the credit system will serve as a powerful lever in the course of transition from the capitalist mode of production to the mode of production of associated labour.”[35] Proudhon would hardly have disagreed. For Marx, abolishing interest and interest-bearing capital “means the abolition of capital and of capitalist production itself.”[36] For Proudhon, “reduction of interest rates to vanishing point is itself a revolutionary act, because it is destructive of capitalism.”[37]

Marx asserted that “Proudhon has failed to understand” that “economic forms” and “the social relations corresponding to them” are “transitory and historical,” thinking that “the bourgeois form of production” and “bourgeois relations” were “eternal.”[38] Yet Proudhon explicitly argued that the “present form” of organising labour “is inadequate and transitory.”[39] Hence the need to “organise industry, associate labourers and their functions.” Association “is the annihilation of property” and this “non-appropriation of the instruments of production” would be based on “the equality of associates.”[40]

Much more including source links here:

Proudhon and Marx