Why didn't Marxs predictions occur?

Answer 1

Marx's predictions, thus far, have been very accurate.

Wage competition and the control of the means of production, as well as increased mechanization of traditionally human-held labor, leads to the widespread misery of the majority with the sole enrichment of a small minority.

Where Marx was wrong: Revolution. Marx, toward the end of his life, believed that an immediate revolution was necessary to stop inevitable collapse and free workers from the oppression of the state and of wage competition. It is important to remember that Marx was alive when the world was plagued with widespread slavery, and women were treated as property. In this context it is understandable that he would find that his "inevitable revolutions" were moving too slowly.

He did however predict that the revolution against the aforementioned causes of decay were inevitable. In the light of the recent financial meltdown, he appears to have been correct here.