Duldong Majiok Deng armed himself with a knife and drank alcohol in an effort to reduce his anxiety, but instead it was a deadly combination for another boy.
Yohana Apai was ready to begin university and start a family with his partner when Deng stabbed him to death at St Kilda beach in October 2021.
Deng has pleaded guilty to manslaughter.
Two families had lost young men as a result of Deng's actions, his lawyer, Julia Munster, told the Victorian Supreme Court on Thursday.
But the difference, said prosecutors, is that Deng's family will get him back again one day.
Mr Apai's will not.
The 24-year-old had been at the beach alone on October 27 when confronted by Deng and others. Punches were thrown and Mr Apai tried to run away.
He was later confronted by Deng who pulled out a knife and stabbed him in the stomach.
While the court heard Mr Apai may have armed himself with a bottle between the two incidents, he had done so after already having been punched twice.
Mr Apai died in hospital the following day.
A family friend said Mr Apai was looked up to by the younger children in his family, and was a leader in their community group.
His children's grandparents in Africa, who hear about young people dying n violence in Australia, are worried.
Mr Apai's death had caused a shock wave, he said.
Psychologist Patrick Newton said Deng had begun carrying a knife for his own protection because he felt it alleviated feelings of anxiety.
It also led him to affiliate with certain people and to drink alcohol, which in turn made him hyper-agitated and reactive.
Being armed, anxious and intoxicated opened him up to considerable risk and was most unwise, the doctor said.
"All of those put together leads to the offending," he said.
"His attempts to manage his anxiety only leads to exacerbate it."
He said Deng had expressed deep remorse at being involved in the loss of someone else's life, and was horrified and ashamed by the outcome of his actions.
He believed with culturally appropriate support and help, Deng's prognosis was positive.
Going back into the community is when Deng would be really tested, because that's when the risk of relapse is highest.
Support structures would need to be in place, he said.
Justice John Champion will sentence Deng on May 2.
