Money, Market and Share.
How many social medias are you a current user of? Just 1, maybe 2, or is it 4 or 5? How often do you access those scial media accounts, just once a day or every time you have a free second? Think about that, most people do have more than one social media account today and most people access their accounts more than once a day. For a business, which company wouldn't want to invest in that large of a market. Businesses pay good money to place ads on social media sites because those ads will be seen by thousands upon thousands of people. Social media is they place to market and with succesful marketing, revenue wil be created.
Top Social Medias
According to Dreamgrow.com, here are the top 5 social medias as of August 2017:
A quote from Mark Zuckerberg, Co-Founder of Facebook:
" When peope are connected, we can just do some great things. They have the oppurtunity to get access to jobs, education, health, communications. We have the oppurtunuity to bring the people we care about closer to us. It really makes a big difference." BrainyQuote.com