Personally, I have never met anyone who started playing Go for the recognition, admiration, or esteem that they felt they would garner or receive from others. I can see how players who achieve fame or who dream of achieving fame through Go, might be examples of this. But those are truly rare cases, considering the millions of Go players worldwide.
Why do people approach anything new? They either perceive that they need it, know that they want it, or suspect they might enjoy it. Curiosity, interest, and pleasure seeking behavior, sparks just about everybody to search for hobbies. Go is no different.
We had a big discussion a while ago about Go and how it correlates to IQ. The general consensus was that Go itself had no influence over IQ. No matter what your IQ is, you may or may not play Go. And if you have a high IQ, then you will likely excel at Go more than people with lower IQ’s. However, IQ has nothing to do with the level of personal enjoyment that one derives from playing Go.
In this same way, why we play Go will boil down to why humans behave the way that they do. Why do they make the choices that they do? How do they logicize, cognize, analyze, and ultimately come to a final decision? It sounds to me like your interest lies more in human psychology, neuroscience, and behavioral science.
There have been some great answers here so far. I’ll add that I think why people quit is pretty simple. For whatever reason a person comes to investigate Go. They give it a try, and as has already been mentioned, it is quite hard to get started. Why Go is hard to learn is a completely different topic, but we all know it to be a fact.
Once they investigate, begin to understand what Go is, what the learning curve looks like, realize Go is a more serious game than most board games or other abstract games they might be familiar with (Reversi, Checkers, Connect Four, etc…), then they are faced with a decision. Do I really want to invest my time into learning this activity? Will this be a good investment? Is it too hard or frustrating? Does what little I know about Go so far, resonate deeply enough to explore this game further?
But the biggest factor that any hobby faces when it arrives at the metaphorical chopping block of human commitment or abandonment, is time. People are living busier lives than ever these days. Their attention is being pulled in a million directions. The digital age has added so many options for ways for us to spend our time, that it almost boggles the mind. When a person makes a decision about picking a new hobby, it is obvious they cannot explore every hobby that peaked their interest.
They must assess all the options for hobbies on the table, as well as consider if their time would be better spent on non-hobbyist pursuits. Should I invest more into my schooling, career, relationships, exercise, non-essential learning, pick up a new skill, learn a musical instrument, finally try my hands at a new language, etc…? With only one life to live and time being a finite resource, people must be very selective. And let’s face it, Go isn’t something you learn in a day.
Depending on their mindset they have when they approach this hobby, Go may be a very poor choice for them personally. If their reasoning or preference for starting Go would require a substantial and long term time commitment to their goal, then Go, again, may be a poor choice. If you are here to compete, know the most, be the best, dream of reaching amateur Dan level, want to follow Go like a sports nut, learn all the Joseki, master the best strategies and tactics, become a 5 second turn Blitz Master, etc… then your Go goal isn’t going to be reached anytime soon.
Meanwhile there may be other hobbies on the table that have attractive goals that might be reached in a substantially shorter period of time. That would leave them free to pursue more goals, new hobbies, or refocus their efforts on new goals in the same hobby. Why we play Go deeply personal, and why some people choose to stay boils down to the fact that they made the conscious choice to, despite all the reasons and opportunities to spend their time elsewhere.
I love Go, you love Go, but not everyone feels as we do. Just as being an Athlete doesn’t resonate with me but represents the world to an Olympian. Another part of this is that as a true fan of Go, you have had the time to get to know various aspects of Go in a way that newbies cannot yet understand.
If I play you a piece of Mozart’s music, you can recognize it’s beauty. But show that same piece to a talented pianist and they will interpret an entirely different world of beauty, with a technical understanding of the music and techniques being applied that your untrained and lesser experienced self can not yet truly comprehend. Beauty is entirely in the eye of the beholder 
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Simply put, I have a growth mindset. I’m in love with experiencing life and understanding the world around me. I am obsessed with competing with myself, ever chasing the goal of becoming a better version of my previous self. I’m a natural born philosopher and deep contemplation, rumination, and daily pondering of ideas and concepts, is my playground of choice. It is my happy place. I love a good conversation, but this endeavor is also equally enjoyable alone. Who doesn’t want to know more stuff 
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@mekriff, @kickaha, @lysnew, @Vsotvep: I have sincerely enjoyed reading your responses. Thank you for explaining these concepts and sharing your viewpoints. I talk about this subject a lot in my life and I found it refreshing to hear familiar concepts worded in new and interesting ways. Truly, I found them informative, interesting, and enjoyed reading them. Thank you for spending the time to share 
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I really think that keeping players initially boils down to making the process clear, concise, and fun. If you can minimize confusion and make the process fun and/or exciting, then you will see a lot more people Trying out Go for longer periods of time. In the end though, as others have so finely put it, staying in the hobby takes a particular kind of person to thrive and find lasting interest.
@Vsotvep’s suggestion about donating Go equipment to school and teaching children is probably the biggest thing a single person could do to bring the largest number of people to the hobby. Entertainment, books, video games, and other ways of teaching Go to kids and teens is also going to have a huge impact. Hikuru No Go is serious successful in this arena 