People forget this act when they think about Gi-hun's humanity.

People forget that in season 2 Gi-hun sacrificed like 20 people in favor of the rebellion against the guards, then he sacrificed 9 other players in the rebellion and prevented that player X from killing the O's.

That single act along with dozens of other dark, cold, and Machiavellian acts make Gi-hun one of the most evil characters in the series, second only to all those directly related to the Squid Games.