My last comment basically covered this
As I spent a few years in a profession that dealt with finding the most probable reasoning behind an act I have found that in most cases the simplest answer is the correct answer; greed, jealousy, etc.
To that end, the simplest answer to the @ranchorelaxo saga, is that he may have profited from the advice of @haejin and chose to show his appreciation through upvoting.
It also seems as if he did not act overly irresponsibly and has since curbed the behavior. Lets assume he made $500,000 and upvoted @haejin 10% of his profit. Not unreasonable...
We will have to see how it plays out...