In the first three verses people are plotting evil against God and God’s response in v.4 is rather surprising. He laughs. I guess it is a bit like the parent who laughs when their four year old stamps their foot and says, I’m leaving home! The parent knows a child hasn’t the resources or knowledge to leave. In the same way those who plot evil against God don’t have the resources or knowledge to do it, unless God allows it. Of course, God doesn’t laugh at the outcome of evil but He laughs at the attitude that says, I can outsmart God or God won’t notice me when I do wrong.
The rest of the psalm makes it clear that God is control, He is running the show according to His agenda and timetable and one day the whole world will see it. In the meantime the advice to us is to “serve the Lord” v.11. We need to be aware that there is a Greater purpose going on then the one we can physically see and remember that it really is all about Jesus and His Kingdom.