As a current college student that operates in a community where I see a number of my fellow classmates using reddit online during class I can say that they would not pay for directly for the service. These days there are too many supplements to Reddit that entertain me just as much if not more.
Although I do believe that Reddit is a very established and well liked website that would still see success if they charged a subscription fee, just not on the same scale of popularity that they currently do.
I think being an introvert helps tremendously when attempting to build a network as long as you are dedicated and passionate about doing so.
Dale Carnegie wrote a book titled "How to Win Friends and Influence People" (which I recommend, its old, but a great read!) where he described that the easiest way to "win friends" or influence people is to have a genuine interest in other people and actively listen and allow them to feel your genuine interest in them.
I find that when I have more introverted characteristics I am able to make more connections because I spend more time listening to other people and less time trying to make myself feel important which helps me to better get to know the person I am meeting and to appreciate and value their characteristics and skills.
Recently I began a summer college job working for an accounting firm with 100 other employees and I only knew about 6-7 people. Over the past few weeks I have dedicated a large amount of time to expanding my network and getting to know my fellow workers on a personal level. Now I find friendly faces all around and I consistently have people popping in to my office area asking if I need anything or just seeing how I am doing and even sometimes popping in to talk about some cool new business that they read about (sometimes even the CEO).
I think that at the end of the day whether you are an introvert or an extrovert all that it takes to start building a network is to find a genuine interest in other people. If you have that you will be pretty successful at what you want to do.
https://www.edx.org/course/introduction-computer-science-har...