I am glad I went. My friend had a good time and would not otherwise have gone. I saw an old friend that I had been close to for many years and had lost track of him. We have rekindled our friendship. It is great to have friends.
Life is short.
Surely you will see someone that you may or may not have forgotten, who you will be happy to see. You may even rekindle an old friendship or begin a new one. Also, people change. That guy who was a jerk in school may have gone through an awakening and now is a sensitive, compassionate, loving funny person. You will not know what you missed if you do not go.