Where do you get the idea that they had high expectations? The whole article is like "I knew this game wouldn't sell, but hey, at least it did better than my first ten games". This person is a grinder and may very possibly achieve moderate success or better if they keep it up. Their trajectory is def normal for successful indie game devs, anyway. You just never hear about the dozen plus games Soderstrom made/released before Hotline Miami or Thorson made/released before Celeste, etc. Because...well, because they failed
This article does serve as yet another good reminder though that platforms are where the money is and that making content is no way to make a living. Make your fuck you money first, THEN make content using the skills you developed along the way. You'll have something to make content about, too, having been out and about in the world to make your nut