I wonder how much of this is the free/paid issue. I think the question here is, how much more would he have made if the app was free, but limited to 15 reads/day, unless you unlock it.
The try before you buy model has been proven a few times over, as he speculates.
Probably says more about the market for another RSS reader than it does about the market for indie developers as a whole.
Even then, assuming his sales continue now at a similar rate post-launch week, without any more development work, he still stands to make $10k or so extra per year. Which isn't bad.
Well it is bad if that's you're only income. This is an on going theme amongst indie Mac/iOS devs at the moment. The really interesting commentary (I think) comes from Gus Muller (developer of Acorn) http://shapeof.com/archives/2014/7/being_indie_in_2014.html and Tyler Hall http://tyler.io/2014/07/a-candid-look-at-the-financial-side-of-building-mac-apps-on-your-own/
Well whilst the money for that keeps coming in, he can work on another, get $30-40k again. Then again, all whilst the previous apps continue to generate money.
Good point well made. In my experience though app sales trend to 0 even with updates.