In verse 5 we read: "A false witness shall not be unpunished, and he that speaketh lies shall not escape." This might seem false as we observe the state of current affairs around us, but we can be confident knowing that God will make things right in the end. God's Word is true and we can trust Him.
Now what do I get out of all this? There is a way that will bring us blessing and there is a way that will end in no good. However, for some instances we might not see that kind of justice occur within our lifetime. If often appears that the wicked are getting by but God is keeping track and his justice will prevail. The writer of Psalm 73 seemed to look at people who were doing well but lived a very bad life. He was envious of them until he went into the sanctuary and realized what their end would be. There maybe those like that who feel that way about our current world today. My attitude should be the same as Christ's. I need not worry about avenging the wrong that others do to me personally or to anyone else. God is the judge of all. One day he will reward both the good (righteous) and the bad (unrighteous) with his perfect justice.