Oswald was a malcontent who externalized the cause of his discontent. In other words, he felt special and blamed others including society for ignoring him. If you want attention but are ignored it is not a happy situation. In the Soviet Union Oswald was, at least for a short time, someone of note. It temporarily satisfied his desire for others to pay attention to him to be considered unique in that circumstance. People were initially interested in him. However, once the spotlight dimmed and he was relegated to a mundane existence, he was unhappy again and left.
Again it's that violent streak that emerged when he came back: "The anger and violence that were to characterize Oswald’s behavior after his return to the United States were barely visible during his time in Minsk."
Even after the short period of attention in Minsk, when people became bored with him, that violent side didn't show up. Marina said he would sometimes slap her with an open hand; in the US it was a closed fist and harder. He really only started violently unraveling when he returned. The Mailer book included dozens of interviews with friends, associates, colleagues of Oswald's when he was in Minsk, people who knew him. To a person they all said they couldn't believe he could murder JFK. They didn't see this dark side to him. He disliked the USSR but didn't externalize an empty life by blaming society; something he did in the US. He was paranoid about the FBI not the KGB (who followed him much more closely). And he ridiculed Americans, looked down at them for their beliefs, said they were naive about how they were being exploited. He never did that in the USSR (right, he knew he'd get into trouble if he did).
But you're correct and sort of making my point: this anti-social behavior came and went; it wasn't ingrained from childhood. When he returned from Minsk and became a nobody again he lashed out the world that he thought was mistreating him. He was quite angry at the FBI, he thought they were persecuting him and was the reason he kept losing jobs and failing. Remember what he told the Soviets about the "notorious FBI" going after him? I don't think that was all play acting in order to get a visa. He believed it.
Anyway, Robert Oswald said that "If Lee had been forced to remain in the Soviet Union he would have ended up shooting Khrushchev." That may have been more tongue-in-cheek than true; but again, that type of angry guy wasn't there in Minsk. Maybe it would have emerged over time; which I think was Robert's point: Oswald was going to be miserable anywhere.
