Chan, 39, who was born into a rich family and was educated overseas, is the chairman of an investment company. Yet earlier this year, he agreed to take part in The Battle of Poor Billionaires. The reality TV show by RTHK documents how the rich and famous fare while living rough on the streets or in cage homes with the city's poorest.
"I had no hidden agenda. I just wanted to see the reality in Hong Kong," Chan says. "I've done charity work myself, too. But I had no idea what it really meant to live like the elderly in cage homes and to salvage cardboard on the streets."
So for four days, Chan lived like a scavenger in a cage home in Kwun Tong. He was given HK$10 a day, an amount cage-home residents living on government subsides often end up with after paying for rent and living expenses.
"The smell was horrible. I was woken up by it at night," Chan says. "During the day, I went out to observe others and noticed a lot of elderly people were picking up cardboard. So I followed suit."
That wasn't as easy as it seemed at first. "It's hard to find cardboard lying around. Some boxes belong to regular scavengers in the district and others go to a recycling company. I got told off when I failed to observe the 'rules'," he explains.
After searching for a few hours, Chan did manage to gather some boxes. He was paid HK$16, which he used to buy bread and apples.
Then, he was assigned to be a "toilet attendant" at a public venue. The millionaire spent the day cleaning and scrubbing. "Standing there for the whole day, waiting and worrying if someone would make a mess for me to clean up - that was killing me," he recalls.
Yet his greatest challenge was to see how elderly people lived, Chan says. "Many of them live alone and without hope," he says. "An old man in a cage home told me his children didn't want to take care of him. I felt bitterly sad."
Something else made him sad, too. "When I met the first elderly person, I thought I could give him financial help," Chan explains. "Then I realised there were so many of them that I knew [handouts] were not the answer."
After the programme, he felt the urge to share his experience with others. He did just that when he received an invitation from YMCA of Hong Kong Christian College. "We were very touched after viewing the episode featuring Johnny and [we] decided to invite him," school principal Nick Miller says. "It'd be a great way to kindle the caring hearts within our students."
Two 16-year-old students, Jose Urbano and Nugent Yeung Ling-tung, have certainly taken away something from Chan's talk.
"It's a nice thing Johnny has done," Jose says. "He went out to experience first-hand how those elderly people lived. We need to experience something to feel it."
Nugent says: "Listening to him reminded me to love my parents more. I wouldn't want them to become like those scavengers."
Chan says he wants students to know they need to care for the elderly. "We should spend time to listen to their stories and not just talk about ourselves. We should respect them. Old people have contributed to our society. They deserve to live a decent life with dignity."