Something must be given for the profits of the undertaker of the work, who hazards his stock in this adventure. The value which the workmen add to the materials, therefore, resolves itself in this case into two parts, of which the one pays their wages, the other the profits of their employer upon the whole stock of materials and wages which he advanced.
The transformation of land from commons to real estate followed a similar logic. Smith assumed that “as soon as the land of any country has all become private property, the landlords, like all other men, love to reap where they never sowed, and demand a rent even for its natural produce.
Most classical and neoclassical economists believe that profits are the just reward for capitalists who risk their capital.
Rifkin, Jeremy (2014-04-01). The Zero Marginal Cost Society: The Internet of Things, the Collaborative Commons, and the Eclipse of Capitalism (p. 41). St. Martin's Press. Kindle Edition.