What does 1 Samuel 8:19 mean?

The Lord directed Samuel to give fair and legal warning to the Israelites (1 Samuel 8:9) about all the things they should expect a human king to take from them (1 Samuel 8:10–17). When those troubles come, God will not be sympathetic to Israel's complaints, since they will have chosen this for themselves (1 Samuel 8:18). Will the people change their minds after hearing that they will effectively become slaves to their own king? That they will risk all their property and servants and even children to be available for his use?

In short, the people say, "Yes! We still want a king over us!" They refused to heed Samuel's warning. The Law allowed them to take a king (Deuteronomy 17:14–20), but it did not require them to have one. Most concerning is that their approach to appointing a king was not guided by submission to God, but by a desire to be like other cultures (1 Samuel 8:4–5). Samuel's wish for them was to avoid it, but the elders of Israel had made up their minds.