"When you get on the boat, you don't think about the people on the shore. When you get off the boat, you don't mention what happened on the boat. Everyone doesn't talk about the world, there is nothing in the world. " It means that the ups and downs of life are common. People should do what they should do anytime and anywhere, and don't care about or ask questions that have nothing to do with themselves.
A sentence similar to "boarding the ship without considering the people on the shore, getting off the ship without mentioning the things on board, telling everyone that the world is nothing on earth" is that "old people don't need to know the present situation, and new people don't need to ask about the past."