Selling drugs only to people who are sick is, by definition, a limited market. Expanding drug revenues requires reaching people who have nothing wrong with them and convincing them that taking a cocktail of daily pharmaceuticals will somehow keep them healthy.
All this is, of course, the greatest quackery we've yet seen from Big Pharma, because once this floodgate of "preventive pharmaceuticals" is unleashed, the drug companies will be positioned to promote a bewildering array of other preventive chemicals you're supposed to take at the same time. Did you take your anti-cancer pill today? How about your anti-diabetes pill? Anti-cholesterol pill? Don't forget your anti-Alzheimer's pill, too.