In my head, i'm trying to figure something. I've seen that Stardew Valley has been sold for more than 1 million copies on steam. It was a game, which was developed by a single guy. That guy, according to Wikipedia, had a major in computer science. That already means he had a strong knowledge about software development in general, unlike us code monkeys who stay on gamedev and stackoverflow, and ask a million questions, just to get a million questions more. Stardew valley is a 2D game, which was developed in 4 years. I've seen the game, and i'm trying to figure, what has took him THAT long? I mean, seriously, the game has a few base game mechanics. The game is 2D pixel art. The code might be thousands of files. What takes 4 years just to develop a 2D game? Answer the most noobish question please.
The artwork takes time to make.... and most of what gets made is thrown away and remade better, during development. What art you see in a game, likely four times more was made and remade before it makes it in the game.
The coding takes time to make... especially when you are learning new tools and game design. Him having a computer science degree may mean he already knows how to program some times of computer applications in one language, but it doesn't mean he knows how to make games in whatever language he eventually decided to use. He likely had to learn entirely different thought processes.
Making a game takes time, in-general... especially when you're also working a job, and can only work on your game after you come home from work (though in this developer's case, it sounds like it was a part-time job).
I've been working on my RPG for nearly six years now - learning as I go. And I've certainly wasted alot of time, partly from inexperience, and partly because that's just how game development goes.