If Christianity promised to produce a “happy, healthy, wealthy” life and failed to do so, then it could be indicted as false. But Christianity makes no such claim. Christianity does promise a full and satisfying life, but it's a life based on loving others, service, sacrifice, and suffering.
Jesus spent 3 ½ years training his disciples to go and make disciples. That’s a rich and satisfying life. He didn’t spend 3 ½ years training them how to achieve worldly success and prosperity. Of course, there's nothing wrong with worldly success and prosperity if it is the byproduct of being a faithful servant. The main business of God, however, is soul–making not money–making.