My boys love the card game Top Trumps, we have various version of the game. If you don't know it the aim of the game is simply to win the other persons card by having a higher number in the chosen category, thus trumping their card. Some of the versions have been played so well the boys don't even have to look at the cards, but know them off by heart.
Hebrews is a bit like a pack of top trump cards. The pastor's point in writing Hebrews is to show how in Jesus we have the ultimate expression of God, and therefore everything is better in him. Jesus, God the Son, provides a better revelation of God than angels - Chapter 1-2. Jesus is better than Moses - Chapter 3. Jesus is a better High Priest - Chapter 4 and so on. At each stage the pastor warns against drifting away from Jesus, from what we have heard, from the salvation he provides and so on.
"But Jesus..." could in many ways be a good two word summary of the book. Hebrews 2v5-9 remind us of our need of Jesus. How the world made to be under the rule of man as the pinnacle of God's creation has been marred and marked by sin. How that is not how the world is any more, that is not what we see. Instead we see chaos and war and decay, sin ruining God's good creation. Then come those words in verse 9 "But we see him...". We see Jesus - God the Son stepping into the darkness, the chaos, the world infected by sin, giving a glimpse of his authority and his rule over it as he raises the dead, calms the storm, feeds the hungry. And ultimately as he breathes his last only to burst through death to new life again, so that by faith in him we may all share in his life, and his coming rule.
Why would you want to drift from him? Why would you forget? Why would you choose not to listen to this good news? How will we ensure that none of those things happen to us? Feed again on what is yours in Christ - we don't earn it - it is given to us by faith.