Pass by in a hurry, why stay? what's the meaning

You will meet too many people in your life, and only a tiny part will be with you in the end. Some people leave with heartbreaking pain, while others leave without feeling anything. Those who left, whether important or not, became passers-by. There are too many passers-by in our life. Those who are unimportant and once most important to us, no matter how important, have left and become passers-by. They participated in our lives, and their departure made us know more, which is the significance of their appearance. Now that they have left, don't dawdle and add to your troubles. Collect it and slowly taste what passers-by taught us in the years to come. This is what I understand. Passers-by are in a hurry, so why stay? Life is bitter: life, old age, illness, death, parting, long-term hatred, longing, and not letting go. When there is less nostalgia for unworthy things, there will be less pain.