So the logic conclusion for you is not that North Korea did this who has no foreign currency and minimal income. But rather it was the NSA who is bankrolled by the US government and who will be receiving additional funds in the upcoming budget process.
One of those groups has the funding and experience to create malware that finds its way into 150000 computers. This group already monitors billions of other devices.
The other is an isolated nation that's decades behind on technology, only recently building weapons that can compete on a global scale, and struggles to feed its starving population.
It wouldn't be the first or even hundredth time that the US gov did something shady and pinned it on an enemy. It's less about the money and more about justifying their expanding powers.
I don't know who did it. I'm just saying it's not a stretch to accuse the NSA given their history with hacking tools becoming public and the Snowden leaks.
To use the revenue generating argument from the OP article as a good indicator of the author is weak at best.