In his latest attack, the Good Morning Britain presenter has accused them of "exploiting" Harry's late mother Princess Diana's death for money.
He discussed the couple's decision to quit the royal family for more privacy and Harry's recent speech about undergoing years of therapy to cope with his mum's death.
It was reported that Meghan and Harry received between $500,000 (£386,232) and $1 million (£772,465) for their appearance at an exclusive JP Morgan event recently.
Writing for the Daily Mail, Piers said: "Harry delivered a speech about his favorite topic: mental health. More particularly, he spoke about how he’s been undergoing years of therapy to deal with the death of his mother Princess Diana. None of this was new territory.
"Harry’s not the only person to ever lose a parent when he was young. It’s sadly happened to many millions of people, including me – my father died when I was one."
Piers said there's a "big difference between talking about it to raise public awareness of grief-related mental health issues" and doing it "privately for a big fat fee to a bunch of super-rich bankers, business tycoons, politicians and celebrities".
He added: "By commercially exploiting his mother’s death to make vast pots of money like this, Harry is surely behaving in exactly the same way he professes to despise from the media?"
It comes after it was reported that Harry has been in talks with renowned US banking giant Goldman Sachs to put he and Meghan in line to earn millions of pounds.
Royal sources told the The Mirror that Harry could soon be raking in the pounds in clever corporate deals with the US bank.
Talks between the Sussexes and Goldman Sachs allegedly started in November 2018, alarming some in royal company who think this deal could massively damage the royal brand.
Last week, Harry spoke at a JP Morgan sponsored event in Miami, sharing his experiences with therapy and dealing with his mother’s sudden death in 1997.
A source claimed to Page Six: "Harry spoke about mental health and how he has been in therapy for the past three years to try to overcome the trauma of losing his mother.
"He talked about how the events of his childhood affected him and that he has been talking to a mental health professional.
"Harry also touched on Megxit, saying while it has been very difficult on him and Meghan, he does not regret their decision to step down as senior royals because he wants to protect his family. He does not want Meghan and their son Archie to go through what he did as a child."
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