Their father was a Hollywood executive, and wealthy. He had a lot of power, and many people were afraid of him. Their mother always put their father first, and not them. They were abused their entire lives by their parents. That's different than an adult woman in a battering relationship, and in both instances, it can get to the point where the victim(s) feel they cannot leave. When the victim leaves or tries to, that is often the most dangerous time, because the abuser doesn't want to lose control over the victim, and doesn't want the truth to come out. People have been killed by their abusers after they leave, it's not a guarantee of safety. Interestingly. actress Dominique Dunne (daughter of Dominick Dunne) is a classic and tragic example of this. She left her abuser, and that didn't save her.
According to a 2017 CNN article, 13% of filicides (children killed by parents) occur when the victims are between 18 and 40 years old. Being an adult doesn't take the threat away. The parents also owned guns, a fact rarely mentioned. There are also domestic homicides that have been covered up and presented as the victim running away or leaving on their own accord.
The brothers' emotional maturity was stunted. A psychiatrist who examined them concluded that their emotional ages were 8 and 10, respectively. Erik had recently graduated from high school and had never lived on his own; even Lyle's time at Princeton was controlled by his father, who frequently flew in to check on him and even tried to control his friendships. They were isolated from their relatives, who also feared the parents and didn't think it was their place to interfere; the police most likely would not have believed them, as I pointed out, one of the police officers stated years later that he and the other cops didn't believe the sexual abuse when it was brought out at trial and described it as "far-fetched". His reasoning was that because Jose Menendez was married and having affairs with women, so he couldn't have molested his sons. That was very outdated and ignorant, and the prevailing attitude back then. They had very little real-world experience and their father controlled the money. What resources? They had no power, or at least didn't think they did. And that's the point. Their mindset was not of people who had a healthy, loving upbringing or had ordinary experiences growing up. They were isolated, massively controlled and were rarely allowed to make their own decisions. They were ill-prepared to live in the real world, thanks to their parents. I don't like to make cult comparisons, but they were raised in a very controlled, cult-like mindset. Lyle and Erik were not raised to be individuals or to be their own person. They were treated like possessions and extensions of their parents.
Their parents being wealthy did not mean that they could have just walked away, and they didn't think they could.
MOO