1 To wear them for protection
Clothes protect people from winters, summers, and rainy seasons. If it is scorching, garments defend our bodies from extreme sunlight and do not let our bodies be sunburnt. Whereas clothes also protect us and make us feel warm when we wear cardigans, jackets, and coats, in extreme winters.
2 To cover our body
The primary function of clothes is to cover our particular body parts, unlike primitive societies that did not believe in covering their bodies at all. One of the reasons for the psychology of wearing clothes in modern societies is that putting on garments has become a symbol of modesty as per the contemporary theory.
3 People want to look good
People wear clothes as they want to enhance their looks and appear attractive. People have started following the approach that only if they have worn smart clothes suiting their body structure; they can look good. Nowadays, you can look out in magazines, TV shows, movies, or advertisements about trendy clothes which would help you look better. (See What makes a person attractive?)
4 To facilitate identification
Wearing appropriate clothes as per the profession of the people makes it easier for others to identify them. For instance, it would be easier to identify a soldier, doctor, police officer, or pilot, if they have worn their uniform.
5 For events and occasions
Some singers wear their particular costumes whenever they are performing live in a concert. Also, people wear exquisite clothes at times when they are about to celebrate a special day, be it their birthday, festival or anniversary. (See Why many people choose to wear branded clothes?)
6 Self Esteem plays a vital part
Clothes give us a sense of Self Identity, and hence, we are what we wear. Many people wear their clothes for the sake of their self-esteem. A rich person is more likely to spend more just to flaunt their money by wearing an expensive dress.