“Everybody’s got dead people. It’s no excuse for getting everyone else dead along the way!”
-Rocket Raccoon
Guardians of the Galaxy

Rocket says this, in particular, to Drax the Destroyer, after Drax, in his mindless, raging desire to avenge his murdered family, has managed to make things catastrophically worse for everyone. And he failed in his quest.

Rocket may be largely selfish, reluctant to follow his own conscience. Yet he understands, and has just witnessed first hand proof, of the disastrous consequences which wait for those who are consumed by vengeance. Nothing, not even something so well-justified as justice for a murdered wife and daughter, gives any man the right to get himself and everyone around him killed. That is selfishness of the highest order, and stupidly counter-productive.

This especially hits home as our colorful cast of characters has been caught in the middle of an interstellar conflict which has left so many people dead. The antagonist himself is motivated by a hatred similar to that which drives Drax. Appropriately, it’s when Drax joins his friends in a fight to save, rather than to revenge and destroy, that they finally win.