Oswald was 24, for what it's worth.
And working at a dead end job - at $1.25 an hour (in today's dollars that minimum wage or less) - that had no possibilities of advancement. He kept getting fired, couldn't hold a manual job, got fired from the one job - the photography one - that he thought had potential. He defected to the USSR, came back, failed at everything he tried, tried to defect to Cuba. He entered the Marines in 1956 as a PFC and left three years later as a PFC. Wife, two kids who have to live apart from him because he couldn't provide for them. He's 24 not 18.
He wants to leave the US because he can't make it here. He's a failure by any measure - he speaks Russian? - but he blamed society, the US, the FBI, for it.