If God has planned everything, why are so many left out?

Because humanity loves evil. Historically humanity has usually almost always chosen their evil ways over God and suffered the consequences for it. He is a loving God who offers us an ETERNITY in Heaven (his kingdom) if we simply obey his will. But if we chose to deliberately disobey and reject his offer of eternal life, we sentence ourselves to Hell. Thus many people will be lost. You don't have to be one of those people if you repent for your sins and turn away from them. I am hypocrite because I do this but yet somehow sin always creeps back into my life. But that's all Christians really. Sin finds a way to crawl back into our lives. But I turn away again and try to repent because I love the Lord and accept and want his gift of eternal life.