What does Proverbs 21:30 mean?

Try as we might, human beings cannot out-think God. Nor can we trick Him, overcome Him, or out-maneuver His will (Job 42:2; Proverbs 10:3; Psalm 146:9). It doesn't matter if the attempt is blatant when someone thinks they can hide their sin from God (Psalm 10:4, 11). It doesn't matter if someone means well and yet thinks they can bargain with the Lord or force Him to act according to their wishes (Deuteronomy 18:20; Romans 2:4; Galatians 6:7). The Lord is absolutely sovereign (Revelation 19:6).

First Corinthians 3:19–20 concurs with this proverb. Paul writes: "For the wisdom of this world is folly with God. For it is written, 'He catches the wise in their craftiness,' and again, 'The Lord knows the thoughts of the wise, that they are futile.'" Psalm 2:2–3 states, "The kings of the earth set themselves, and the rulers take counsel together, against the LORD and his Anointed, saying, 'Let us burst their bonds apart and cast away their cords from us.'" Verses 4 and 5 depict the Lord as laughing at the nations' insolence and speaking to them in His wrath and terrifying them. Revelation 20:7–8 prophesies a worldwide revolt against the Lord at the close of His thousand-year reign on earth. But the attempt ends in a horrific judgment and God's inevitable victory (Revelation 20:9–15).

The next proverb phrases this same idea in military terms (Proverbs 21:31).