Samantha insisted the Duke and Duchess of Sussex should focus their time on their loved ones rather than chasing after new business opportunities during the pandemic.
She continued: "I would suggest that they really focus on the priorities in life – people loved, the nuances in life.
"All of the money and everything else they think they have is totally fleeting and elusive, the emphasis is definitely on the wrong syllable.
"And I think we all get that now and unfortunately it takes a tragedy to shake us to get to our senses."
READ MORE: Meghan Markle and Harry could take DRASTIC measures to solve security rift
The Duke and Duchess of Sussex last week left their temporary home in Canada to relocated to Meghan's hometown of Los Angeles.
The move reignited the debate on who will shoulder the cost of security for the couple and their 10-month-son Archie now they live in the United States.
News of Meghan and Harry's arrival in LA prompted US President Donald Trump to announce on Twitter his Government will not fork out the money to protect the Duke and Duchess.
President Trump wrote: "I am a great friend and admirer of the Queen & the United Kingdom.
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"It was reported that Harry and Meghan, who left the Kingdom, would reside permanently in Canada.
"Now they have left Canada for the U.S. however, the U.S. will not pay for their security protection. They must pay!"
But a spokeswoman for the Duke and Duchess of Sussex said on Sunday the couple had "no plans" to ask the US Government to pay for their security.
The spokeswoman said: "The Duke and Duchess of Sussex have no plans to ask the US government for security resources.
"Privately-funded security arrangements have been made."
Meghan Markle and Prince Harry officially stepped down from their roles as working royals on March 31 after negotiating a one-year trial with senior members of the Royal Family. Under the new system, the Duke and Duchess of Sussex will be able to pursue independent business opportunities without the restraints of royal protocol and etiquette. But Meghan and Harry have come under fire for the decision to go ahead with their move away from royal life while the coronavirus pandemic rages on across the UK.
Speaking to talkRADIO host Dan Wootton, Meghan's half-sister Samantha Markle said: "Those two abandoned the British people and the British people at such a critical time, it takes me back to the Roman Coliseum, it just seems so horribly cruel.
"There's no other way to slice this apple.
"Furthermore, to ask the taxpayers to pay for their security when people don't have resources, they are dying, the world is struggling for their lives, it's incredible grandiose.
"This is historically unprecedented narcissism and grandiosity."