Even rich people can only eat three meals a day (meaning that no matter how rich you are, you can't eat more)
Even if you have thousands of tall buildings, sleeping at night is only six feet wide.
This sentence should come from an exhortation chapter such as Augmented Xianwen, warning people that wealth is infinite, but people's lives and needs are limited. Therefore, don't pursue fame and fortune excessively, accumulate more virtues and do good deeds, and understand the connotation and significance of life.