I relate to this a lot, having also started and then not finished a lot of games like the author.

Perhaps it seems obvious to say, but I have only recently fully internalized that making games is not the same activity as playing games, and that it will take many orders of magnitude more time to polish even one gameplay feature compared to how long it will take for that gameplay feature to become stale _to me_ as the dev playtesting that feature over and over again.

I wonder if a lot of gamedevs just get tired of playing their own game and thus don't care about it anymore as a result?

Seth Godin has a book called The Dip about the slog in the middle that many creative projects have (business starting as well). I wonder if gamedev has a particularly nasty dip and that is why so few finish.