[stinos]

This seems to be 'mysterious' because of the writing skill of the author.

While 'mysterious' is hard to quantify objectively, the thing is: it is not known for sure what it is yet widely available, sounds mysterious enough, right? Or is your point that it actualy is known, but the author doesn't happen to know?

it could have been easily found out by offering 10X-50X

What makes you so sure the author can easily come up with what you call an 'annual income perhaps', just to pursue some story?