In their Communist Manifesto, Marx and Engels identify proletariats as a class of modern workers, whose lives depend on how exactly they may find work. The proletariat has to sell themselves part by part, as they have already lost their characteristics of autonomy. Because of frequent division of labor and unbelievable development of technologies, the nature of proletarian work is all about some kind of addition to the already working machines. Marx and Engels also compare the work of the proletariat to an army, where workers become foot soldiers and spend all their time under commands of officers. Such nature of work turns out to be more terrible when the proletariat plays the role of bourgeois servants every day and every night, and at the same time, they are enslaved by their controllers and the machines.
If the bourgeoisie undergoes certain changes and develops, the proletariat develops in the same ways. This is why all those ideas, which the bourgeoisie has already used against the feudal society, now, maybe turned against that very bourgeoisie. As the bourgeoisie has already achieved certain success and prosperity, it forgets about those powerful means, which helped to gain recognition. And the representatives of the bourgeois society cannot even guess that all their means may be now used by the proletariat, who is now under a terrible pressure, in order to achieve the same success and destroy the bourgeoisie as well as it has already destroyed the feudal society.
At the same time, the “dangerous class” was the social scrum, the lowest layers of old society with the lowest conditions of life. This group of people is considered to be dangerous, because they may serve as a bribed tool for both the bourgeoisie and the proletariat. This dangerous class could be easily re-organized by either the bourgeoisie or the proletariat into one movement in order to fight against each other and win because of the variety of people.