Why can’t Trump accept his defeat?

With his defeat in the US presidential election, Donald Trump finds himself fighting against being tagged with a label he frequently applies to rivals but which runs completely counter to his own brand: "loser."

The Republican is pursuing legal action in several battleground states, though his lawyers have so far failed to substantiate claims of fraud and observers see the possibility of the courts overturning the result of the vote as vanishingly small.

Yet according to scholars and mental health professionals, the same authoritarian qualities that defined Trump's rise to power and his presidency make it almost impossible for him to digest a graceful concession to Democratic President-elect Joe Biden.

This, they warn, could make the post-election, pre-inauguration period a particularly unstable time for the country.

A growing number of mental health professionals have publicly warned that Trump is a "malignant narcissist." People who have this personality type exhibit narcissism, antisocial personality disorder, paranoia, and sadism.

John Gartner, a Baltimore-based psychologist said he was worried that Trump may attempt to pursue a "Nero decree" or "scorched Earth" strategy as a means to deal with his loss.

For Mary Trump, the president's niece and one of his most strident critics, her uncle's decision to declare himself the winner of the election and accuse his rival of cheating spoke of his desperation at circumstances he wasn't accustomed to.

"Donald has never been in this place before where there's nobody to bail him out, there's nobody to buy him out," the clinical psychologist, told MSNBC.

Trump has built his public persona on the idea of being a winner in every field.

Lawrence Douglas, author of "Will He Go? Trump and the Looming Election Meltdown in 2020," argued there are prudential reasons why remaining in high office is beneficial.

In addition to being hundreds of millions of dollars in debt, he is facing defamation cases by women who have accused him of sexual misconduct and even potential criminal charges stemming from his business practices -- with his immunity ending when he is no longer president.

But beyond that, Trump's refusal to concede helps keep his connection alive with his base, said Douglas. "Even in defeat, this way his brand will remain irresistible to his supporters."