Who gave him charge over the earth, and who laid on him the whole world?
The scope of Elihu's discourse to reconcile Job to his afflictions and to pacify his spirit under them. In order to this he had shown, in the foregoing chapter, that God meant him no hurt in afflicting him, but intended it for his spiritual benefit. In this chapter he shows that he did him no wrong in afflicting him, nor punished him more than he deserved.
Commenting on Job 34:10-15
If he set his heart upon man,.... Not his love and affections; though there are some he does in this sense set his heart on, and whose souls at death he gathers to himself, but with this sense the next verse will not agree; but to destroy him, as Jarchi adds by way of explanation; if he gives his mind to it, is set upon...
If the world were not God's property, as having been made by Him, but committed to His charge by some superior, it might be possible for Him to act unjustly, as He would not thereby be injuring Himself; but as it is, for God to act unjustly would undermine the whole order of the world, and so would injure God's own property (Job 36:23).