[Jesus]... though He was in the form of God, did not count equality with God a thing to be grasped
We want equality with God. We think we deserve to be in the position of God in our own lives. We operate as if that's the position we occupy. We pray as if God is our consultant or our co-pilot, we still try to retain the authority ourselves. This attitude is the root of our sin. We sin in a particular situation because, in that moment we think that we know better than God. This shouldn't catch us by surprise us because it's exactly what happened to Adam and Eve, the serpent telling them that, if they eat the fruit which God had told them not to, then "your eyes will be opened, and you will be like God, knowing good and evil" Genesis 3:5. They wanted equality with God, and so do we.
Fortunately for us, Jesus, who had equality with God, gave it up on our behalf. This verse tells us that Jesus didn't consider equality with God something to be grasped. We try desperately, and pathetically, to grasp it but He had it and gave it up, becoming a man to ultimately die in our place, because of His great love for us.