Didn't do anything.
This is basically a reverse on mc, what happend to hyun do in this life is the same as when MC got mad with hyun-do in his previous life. MC got wary and worried that hyun do might just only be pitying him because of his financial and family situation, there's a mix of jealousy too because hyun do is a prodigy (still is in MC current life tbh) and thought hyun do was just glazing.
The difference was the current hyun do manage to fully mend their relationship before it was too late while, mc was too late to retract/ took back his words.
Though, hyun do's didn't experience financially stressed like MC did in his previous life. The feeling and experience is similar with one another.
What did hyundo do in the previous life to make MC wary of him?