When companies are looking to raise capital & expand, they will often have an initial public offering (IPO <example here>). Without drawing out this analogy with all the benefits & disadvantages of such a decision, suffice it say that if you have something of value to offer over an extended period of time, this can be a very good move.
I have read many articles encouraging people to expand their web presence; my publicist chewed me out last week due to my under-exposure, & rightfully so (hence, this blog, for instance). For the individual, “going public” means presenting as many opportunities as possible for people to invest time in you. There are people on Twitter who could probably raise several thousand dollars at a time by offering a service or product to the people that they are exposed to, namely because of all the free help they provide on a daily basis. There are people in every line of business presenting free information, entertainment, etc. that anyone can have access to, & their public appreciates this; that appreciation can work the same way a dollar can. When your money appreciates, it increases in value; when you are appreciated, you will increase in value.
Twitter, Facebook, & the rest can be fun ways of passing time, but if your accounts are unable to collect enough interest, they will not do you much good. Think about it–do your friends just come to you now & put money in your pocket for being sarcastic, cynical, & ridiculous all day? Do they pay you a dollar every time they read what you had for lunch, where you’re going, or whatever other random thing comes into your mind to tell the world? Probably not. Even if you are one of the more interesting more in your circle, you may be like a savings account that accrues more interest than with other banks, but still a relatively low amount of interest compared to all of your options (as with other more rewarding opportunities, however, the risk normally increases–but that is a topic for another post).