Marx and Engels claim, in the Communist Manifesto, that what will cause the fall of the bourgeoisie is a proletariat revolution against the bourgeoisie.
They believed that the proletarian people (working class) will resent after being constantly exploited by the upper class (bourgeoisie), and this would eventually lead them to do a revolution against them as well as to overthrown the capitalist system and its supporters.
After the proletariats' defeat capitalism, a new classless society will emerge called communism, which is based on the idea that all people would have the right to have the same land, labour, education, health and wealth. In other words, everything should be shared among all the people.
