“Stockholders toil not, neither do they spin, to earn and share price increases. They are beneficiaries by position only. Justification for their inheritance... can be founded only upon social grounds... that justification turns on the distribution as well as the existence of wealth. Its force exists only in direct ratio to the number of individuals who hold such wealth. Justification for the stockholder's existence thus depends on increasing distribution within the American population. Ideally the stockholder's position will be impregnable only when every American family has its fragment of that position and of the wealth by which the opportunity to develop individuality becomes fully actualized.”