It's Safer. You can raise a family or grow older in a wholesome, safe environment.
It's Healthier. Medical researchers find that people live healthier lives if they have many social connections, particularly as they get older.
It's Cheaper. Shared resources and economies of scale reduce the cost of living.
It's More Satisfying. You can experience a sense of connection and support with like-minded friends and colleagues.
You'll Grow as a Person. You will undoubtedly become more self-aware, and possibly more tolerant and compassionate. You'll learn better communication skills, and will become better at participating in meetings. You can learn new skills in other realms. And you'll probably develop more self-reliance.
It's More Fun. You can experience the child's delight of sharing life's pleasures with friends.