Affluenza is defined as a psychological malaise supposedly affecting wealthy young people, symptoms of which include a lack of motivation, feelings of guilt, and a sense of isolation. I do not quite understand the question, but I think it is obvious that affluenza should not be seen as a criminal defense. I fail to see how crushing poverty fits directly into the comparison.
Affluenza should not be a criminal defense, because it is the rich who have had every opportunity in life. The rich should know better. Even if they don't, that is all the more reason that they need a harsh punishment when they do commit a crime, so that they will learn acceptable behavior.
First, I'd like to start by saying that neither topic, affluenza nor crushing poverty, should be able to be used as a criminal defense. The law should be the law applied evenly across all situations. If you break it, then you are unfortunately punished appropriately according to your crimes. That being said, crushing poverty should be the more lenient of the two. If you "suffer" from affluenza, then you have lived a life in which you have generally had all of your wants and desires. I cannot buy into the fact that you become so removed form reality that you don't understand the concepts of right and wrong. At least with crushing poverty, your crimes may be motivated from a basic need of survival (i.e., you steal food because you're hungry). Being in poverty doesn't excuse you from breaking the law, but at least it provides a rational basis as to why someone may commit crimes.
Actually neither of these should be a criminal defense in toto, although one could use crushing poverty and abuse as a partial defense because it is deprivation. It is ridiculous to put affluence into the same category because affluence gives choices rather than taking them away and so is not going to force anyone into anything.