Adam Clarke on Job 18:4

He teareth himself in his anger - Literally, Rending his own soul in his anger; as if he had said, Thou art a madman: thy fury has such a sway over thee that thou eatest thy own flesh. While thou treatest us as beasts, we see thee to be a furious maniac, destroying thy own life.

Shall the earth be forsaken for thee? - To say the least, afflictions are the common lot of men. Must God work a miracle in providence, in order to exempt thee from the operation of natural causes? Dost thou wish to engross all the attention and care of providence to thyself alone? What pride and insolence!