The 63-year-old never married and never had children, but the children were very important to him. He raised a few children and took care of his brother, Daniel, who had an intellectual disability.
Naiman became a social worker after leaving a career in banking.
"He was a valuable employee, reliable and dedicated to his work," CNN Debra Johnson, spokesman for the Washington State Department of Children, Youth and Family, told CNN.
He has worked three times to move into the new field, his friend Shashi Karan told CNN.
Karan and Naiman worked together at the bank in the 1980s and remained in touch over the decades until his death on January 8, 2018.
"He was just that kind of guy that he could not just spend money on." It was just in his nature to save money and put him out of his pocket. side, "said Karan.
Karan said that he was one of the few people who knew how much money Naiman had.
"I think he always knew that he was going to leave his money to a charity," Karan said.
The friends had talked about investments and savings over the years and when it was time for Naiman to make a will, he asked Karan to be his executor.
He added that Naiman had received a considerable inheritance on the death of his father, which had contributed to his fortune.
The search for grimaces, savings and transactions was more of a hobby for Naiman than a sacrifice.
"Saving money was sort of a game for him," said Karan. "He boasted of spending a whole day without having to spend a dime."
Naiman loved cars, and when his brother died in 2013, he made a splurge by buying a Scion FR-S sports car.
"It's a nice little sports car, but it's not a Mustang, a Corvette or a Porsche that it could have easily afforded," said Karan.
Naiman was planning to travel more or buy a house with a nice view, but his cancer interrupted his plans.
Karan said that after his diagnosis, Naiman had spent a lot of time searching for charities.
The Pediatric Care Center for Pediatric Care, which cares for medically fragile babies with prenatal drug exposure, is one of its benefits.
"We are very grateful to Alan not only for his legacy, but also for the life he has dedicated to children," the group wrote.
Karan said the donations mainly involved children's charities, including Father Flanagan's Make-A-Wish, Boys Town and Treehouse, a non-profit organization that helps foster children. He has also donated money to his parents' Catholic Church and to disabled veterans in the United States.
Naiman was excited to think of the good that his money would make at the right time, Karan said.
"My gift will be bigger than their annual budget, it will blow them up," recalls Karan. "And that's what happened."