Can someone explain to me why my answer got that highly ranked?
Besides becoming a HNQ (see here), people evaluated your answer as useful.
Research effort is only one variable among other which is determinant for usefulness. Simple as that.
In addition to the HNQ prominence, I think people (myself included) tend to hit the "this answer is useful" selfishly rather than altruistically. It would be appropriate to click that up arrow anytime one feels, as an impartial reviewer, that the answer is well-written and answers the question posed well. But we're more likely to do so if we ...