"Affluenza" as a defense to manslaughter?

Sixteen year old Texan Ethan Couch was recently given probation for mowing down and killing four pedestrians with his Ford F-350 while drunk.  Couch and his friends began the evening by stealing two cases of beer from a store.  Then Couch, with a blood alcohol level of .24 and combined with Valium, proceeded to speed around in his truck with his friends until he slammed into four pedestrians, killing them all.  Couch subsequently confessed to intoxication manslaughter.

At trial, Couch’s expert witness explained that Couch suffered from “Affluenza,” described as an inability to make good decisions due to a lifetime of spoiling and permissiveness by Couch’s wealthy parents.  The end result?  The judge sentenced Couch to ten years probation (not even a single hour of public service!) and some time at a $450,000 a year rehab center in California paid for by his parents.

Contrast this with the many people currently incarcerated for years, their lives completely ruined, for smoking marijuana by themselves in their home harming no one and ask yourself, does this make sense?