You could equally read it as "There are 7 billion people in the world and these are the 70 people most dependant on them for their power, wealth and security."
Of course, if you took away the other 6,999,999,930 away, the 70 that "matter" would find life infinitely harder. So perhaps we aren't as pointless the title suggests.
When I saw the title I thought it was about social networks: there are 7bn people in this world and you only care about 70 of them. I imagine that could be equally true.
Forbes is pretty silly. Those people have much less power than they think. The #1 ranked person has a good chance of losing his job in a year.