I have argued elsewhere that in past history, freedom of speech, whether granted to few or many, was granted as bestowing some important benefit. John Stuart Mill, for example, in On Liberty, saw it as enabling us to learn from each other through discussion. By the test of benefit, I here argue that social media that are funded through trade in our personal data with advertisers, including propagandists, cannot claim to be supporting free speech. We lose our freedoms, if the personal data we entrust to online social media are used to target us with information, or disinformation, tailored as persuasive to different personalities, in order to maximize revenue from advertisers or propagandists. Among the serious consequences described, particularly dangerous because of its effect on democracy, is the use of such targeted advertisements to swing voting campaigns. Control is needed both of the social media and of any political parties that pay social media for differential targeting of voters based on personality. Using UK government documents, I recommend legislation for reform and enforcement.