In short
John did not wear fine clothes in his service to a king, but rather lived in the wilderness, and later in prison, rather than in a palace, as God’s ambassador, with a coat of camel’s hair (Matthew 3:4).
The people had not gone into the wilderness to see a courtier—one who wears splendid clothing and is always ready to serve the king. John was not to be found in the palace of the king, but in the wilderness—and now he is in prison. He was no courtier of an earthly king, but an ambassador of God, who proclaimed the Word of the Lord. For that reason he had no interest in earthly splendor, but wore a cloak of camel’s hair (Matthew 3:4.1
8 What then did you go out to see? A mandressed in soft clothing? Behold, those who wear soft clothing are in kings’ houses.