The person without it is twisted and dysfunctional. Ingratitude is manifested in many Disgruntled feeling spring up and we are not satisfied with what we have. We somehow think we are entitled to more. Murmuring in the desert against Moses, the Children of Israel were far from giving thanks to God for delivering them from bondage. They were expecting more than that.
Gratitude likewise shows itself in impatience.
Like Saul with the Amalekites, men cannot wait on God, and thus become disobedient, Laziness is another means by which ingratitude manifests itself. Slovenly forgetfulness breeds ingratitude. All but one of ten lepers that Jesus healed were in too much of a hurry to come back to give thanks. But failure to be thankful always will be accompanied by a false sense of values. Proper appreciation will always be accompanied by thanksgiving.