Some people spend so much time learning calligraphy. Is it really good to learn calligraphy? Will it be a waste of time to spend it on other things?

This is a personal interest. Everyone's choices, family environment and hobbies are different. If you don't want to make money and don't worry about material things, you certainly have more time to do your spare time. If you need to earn money and realize your dreams, it may be successful to spend time doing something now. If you don't want to make money, you will live happily if you want to realize your dreams. Therefore, it is not a loss to learn calligraphy, an artistic activity that cultivates the soul. At least it has mastered a good hand and found happiness. It's a waste of time for you, but it's a wealth for others to learn a skill.