1) The market value of a social network with 0 users is 0. This would be true if you were at 100% feature-parity with Facebook. You're not.
2) There are a couple of ways to make money with OSS. I strongly suggest moving away from the consumer Internet onto the producer Internet with your OSS endeavors if you want to make money. This gives you a lot of attractive options, such as a) solving the problems of companies which otherwise would have to pay $20k per month per engineer to solve those problems and then b) selling them consulting services priced with regards to the value you will create for their businesses.
For example, I have OSS A/B testing software. That fact plus a history of publishing regarding A/B testing and achieving results with it makes me pretty darn useful to other software companies. I do occasional consulting on how to implement A/B testing at software companies, generally less on the code side and more on the "What should we test? How should we test it? Can you get us started?" side and price that service appropriately, with a salespitch sounding something like "So what would a 5% lift in your conversions at this point in the funnel do for your business? Cool. I think my project rate will be only a fraction of that, and my clients get 5% lifts all the time."
3) Code isn't valuable per se. Solving problems is valuable. To solve problems with code, you will often have to market that code directly to people who have the problems your code will solve. Engineers often think that the act of uploading code to Github will make magical things happen for them. They are sorely mistaken.