Why does this honest official Harry, who can't even afford meat, pay for three concubines?

It costs money to take a wife and concubinage, which is common.

People with a good reputation may not spend money, but sometimes they can make money from it.

You know, when a woman gets married, her family usually gives her a dowry, while businessmen with money and no power usually post a lot of dowry when they marry a high official or celebrity. Even a poor scholar can find a rich old father-in-law to support himself because of his scholar status. Once a high-ranking celebrity like Harry says he wants to take a concubine, rich people will rush to give their daughters a dowry. After all, they are related to such a person.