When people at different levels can't get the demand at the corresponding level or the demand at the previous level,
People will feel depressed and disappointed.
For example, you already have physical and safety needs, but you have no friends and no one likes them every day. When you see people around you in groups, or couples show love, you will feel that you are a loser with a sense of belonging, disappointed in yourself and have self-doubt.
However, some people are unique, and some people just enjoy being alone, because no one is more interesting than themselves. Such a person needs a strong heart and a secular attitude.