I think there is an echo here of the old Marxist rant against "traitors to their class".
If you worked for a living (and who doesn't?) then you belonged to the Proletariat and you had an obligation to support the great Socialist revolution. If you opposed the Revolution, you were a traitor to your class -- which is to say, you were acting against your own interests.
You’re right about its Marxist origins. They recycle propaganda all the time.