Not exactly. Here's the real quote and its author.
Democracy is the theory that the common people know what they want, and deserve to get it good and hard.
H. L. Mencken
It's from the definition of Democracy in the chapter entitled The Jazz Webster. It's only the second half of the definition. The first part is:
The theory that two thieves will steal less than one, and that three will steal less than two, and that four will steal less than three, and so on, ad infinitum
It's even more appropriate for our new Socialist Overlords than the second part....