He has shown you what is good. … To act justly and to love mercy
Mercy is in many ways the opposite of greed. Greed is taking all we can get, by law, by force, by whatever means. Mercy is leaving something, maybe everything, for others.
A judge knows all the punishments (s)he can give to a convicted person. Conversely, (s)he knows all the rights (s)he can take away: life, liberty, money, possessions. A judge who shows mercy leaves some or all of that to the convicted.
A land owner may leave some of the harvest for birds, animals, human gleaners. (S)he does not take all (s)he can.
An ungreedy (merciful) person making a business deal can leave something on the table.
Mercy builds a more robust community. People don’t have to beggar their neighbor in their everyday dealings. That spreads the resources around for when there is a crisis. Bitter, impoverished people are unable to help each other.