Unfairness

Why would one not be able to live as a person who tries to get along peacefully with everyone? Does one have to be a little obnoxious? Aren't we all supposed to pat each other on the back and aid each one another? An Asian saying goes like this: "When a pig is gutted, one will find that it's guts are filled with excrements." How come one must be careful and not fall into traps? Could one not roam around comfortably? Can't we all just not look at each other's benefit and thus at the end benefit ourself?