Actually even in cases [failed theists] such as you describe, they are "observing the world" and finding that atheism does not fulfill what they know of the reality of being human.Nolo contendere. Atheism has never pretended to be a fulfilling philosophy for the reality of being human. All atheism is a rejection of God as being fulfilling for the reality of being human. This may be done for many reasons. One of the more common is the “hiding” from God. While this meets the definition for atheism it is a weak sort of atheism ready and willing to grab the God life saver when they can’t cope with reality.
Until one has replaced the big two of morality and death as mediated by God and come up with a coherent worldview that is both moral and realistic about death that does not involve God atheism is simply a meaningless label to fool the self and hopefully others.