George Kao"LinkedIn remains especially popular among college graduates and those in high-income households. Some 50% of Americans with a college degree useSee more LinkedIn, compared with just 9% of those with a high school diploma or less."
"Fully 74% of Facebook users say they visit the site daily, with around half (51%) saying they do several times a day."
Interestingly, of the people who use any of these: Twitter, Linkedin, Youtube, Snapchat, Instagram, Pinterest.... 90% of them also use Facebook.
Therefore: If you get good at Facebook Ads, you can reach the vast majority of social media users.