Mr Richards, 56, decided to make the trek to prove it can be done, and to teach his 13-year-old son to stand up for women and children.
His decision came after two refugees set themselves on fire last year and his son Ned asked what could have been done to prevent it.
"I said, 'well, nothing'," Mr Richards told SBS.
"I was going to add, 'because the government doesn't care'."
He said the look on his son's face sprung him into action, and the pair set upon their journey three days after Christmas.
"I've taught him that men stand up for people who need help and I've taught him that men protect women and children," he said.
"In that look and in that moment, I had to confront the fact that I couldn't teach that to my son unless I was prepared to live it."
Mr Richards arrived at Parliament House on Wednesday, quick to point out it was the "dumbest idea" he'd ever had.
"But the intent is to raise awareness and having spoken to so many people on the way here I know the heart of the average Australian, and it's a warm place there," he said.
"No Australian would take somebody that's calling for help and just turn them away, that's just not the way we are."
He arrived in Canberra as a cloud hangs over Australia's refugee resettlement deal with the United States and he hoped the arrangement would go ahead.
Mr Richards slammed US President Donald Trump's labeling of the more than 1000 refugees as "illegal" and pointed to the Migration Act and United Nations Refugee Convention.
"It is lawful to try and save your life, it is lawful to try and seek asylum, the government knows it," Mr Richards, who is a criminal lawyer, said.
"The fact that President Trump doesn't understand international law has been demonstrated elsewhere.
"If Malcolm Turnbull can make that deal work then good on him, but the bottom line is he's doing it to save face. If that gets them off the Island then so be it.
"Anything that gets them out of there, I'm supportive of."
He chose Canberra as the final destination in the hope of delivering a petition when he arrived, and he has been surprised at just how many people wanted to sign it.
"People are horrified and it's people you'd look at and think 'oh they'd never be interested','' he said.
"They're truckies, elderly people, and people driving BMWs. It's amazing the amount of support there is."
With the on-road support of their family friend Pat Hill, Adam and Ned walked 30km a day in scorching heat, bandaging their feet to cope with blisters "the size of your heel".
In order to make their deadline, they had to get up as early as 2.00am some days, but said it was all worth while.
Mr Richards arrived wearing the same black sneakers he left home with, which were cut open into the trip with an angle grinder to stop blisters.
The first thing he'll do when he gets home is have a "nice long, hot bath".
A new pair of shoes is second on his list.