Actually finishing a game is really hard work, which is also why its so awesome if you manage to do so. In fact, I have learned over the years that playing games sometimes makes me avoid doing hard work towards a distant goal (i.e. finishing a game). The problem here is that playing games gives me instant gratification: the sense of having achieved something such as acquiring a virtual new sword with +1 to awesomeness or a pile of virtual clay to bake into virtual bricks, without doing really much. Usually in a well-designed game I get a constant stream of small experiences of gratification (new items or resources, points, etc) for each small thing I do.
Developing a game is not like that at all. Maybe a little at the beginning when you just toy around a bit. But working towards completing a polished game is more like long periods of struggling in frustration with that One Nasty Bug, picking up the work even though I feel I would rather have some instant gratification. Its hard and its not always pleasant.
But in the end the game development activities are endlessly more rewarding and fulfilling for me. Everyone can get an utterly meaningless sword of awesomeness by repeatedly clicking a button for a gazillion times, but few people actually manage to bring a creative effort such as developing a game to fruition. So on the long term I’m definitely happier if I do manage to complete my projects. One thing that helps me a bit is doing at least 5 minutes of game development every single day, and putting a big green marker on a calender for each of the days in which I did that as a reward. This helps me get a bit more of instant gratification and challenges me to get longer streaks of marks by working for multiple days on a row on the project.
In the end, though, nobody is forcing you to complete anything. This is about what YOU want to do. Just think carefully about whether what you are doing is a matter of always giving in to instant gratification, an whether you would feel better in the long term by working on your project.