A wealthy Texan teen received a probation-only sentence after killing four people while drinking and driving, outraging families of the victims.

Ethan Couch, 16, was given 10 years' probation after his defence called himself a victim of "affluenza", a product of an affluent family who have never set limits for him.

The judge ruled that Couch did not deserve any jail time as he was a defendant in need of treatment and rehabilitation himself.

Prosecutors demanded Couch serve 20 years in prison for killing four people in a crash in Fort Worth, but were left furious after the ruling.

"He'll be feeling the hand of God, definitely," said Marla Mitchell, whose daughter was killed in the crash.

"He may think he's gotten away with something, but he hasn't gotten away with anything."

Eric Boyles, a father who lost his wife and daughter in the crash, said that the wealth of the Couch family helped Ethan avoid prison.

"Money always seems to keep you out of trouble," Boyles said.

"Ultimately today, I felt that money did prevail. If [Couch] had been any other youth, I feel like the circumstances would have been different."

Psychologist Gary Miller was called as an expert defence witness and claimed that the boy suffered from "affluenza" as he grew up around parents who argued and then divorced.

Miller said of Couch's parents that "he [the father] does not have relationships, he takes hostages" and "her mantra was that if it feels good, do it."

Couch is set to attend an expensive rehab facility in California, where his parents will foot the $500,000-a-year bill.