Yes, you're missing something very important: You're missing the joy and peace that come from knowing God in a personal way. You also are missing the hope that comes from knowing that someday you will be in God's presence forever.
But I'm afraid your friends are missing something, too! God doesn't want us to live dull, cheerless lives, but lives of joy and expectancy. Jesus said, "I have told you this so that my joy may be in you and that your joy may be complete" (John 15:11). Think of it: When we know Christ and follow Him, He is with us every moment of the day, and we are now part of God's family. Why shouldn't we be joyous?
Does this mean God wants us to ignore the suffering of others, or that He doesn't care if we live self-centered lives that ignore God's command for us to turn our backs on sin? No, of course not. Jesus wept at the grave of his friend Lazarus, and He wept too over the sins of His people. But when we know Christ is with us, we experience a deeper joy -- a joy that isn't dependent on our outward circumstances.
Don't let the shortcomings of a few keep you from Christ. God loves you, and living for Christ can be the greatest adventure you'll ever know. Open your heart and life to Him -- and then help your friends discover the wonder of Christ's joy also.