It took me 3 months to figure how to make an arcade shooter clone with the basic meat: like collision detection, adding monsters and skills and ship health system, adding music and adding gameover on top that I also have college coursework. I worked long hours in the span of 3 months and it's still not done since there is so much I wanted to add like a button-based menu. This is also taking into the fact that I am experience with the language but adding features to the game seems a bit abstract but if you start applying the programming concepts, it makes sense and does not appear abstract as it was before.
That project taught me a videogame can be made by one person if you are super dedicated and passionate about your game getting done. Notice I said made and not finished. There will be some concepts you need to know along the way and figure out with a bit of research. It can be done since I been working on mine for the past 3 months. I would not have learned so much on my own if I did not start this video game project.
Just remember: it is all about having fun working on it and being serious about eliminating bugs from the game. It is important to finish a project than have one that is not finished.