There are several very good reasons.
History helps people to understand the relationships between past and present.
History helps people to understand their world. History is a story of love, hate, war, compassion, creation, discovery, lust, heroes and villains. In other words, history teaches us about issues which remain important today. Best of all, we can look at the achievements and mistakes of others, and learn form them to improve our own lives. As an individual, you are the sum total of all your experiences.