The real puzzle is why he ever left his comfortable exile in England in the first place.
In theory Musharraf, who seized power in Pakistan in 1999 and finally gave it up under great pressure in 2007, could face the death penalty if he is found guilty, but in practice he is protected by the Important Persons Act, an unwritten law that operates in almost every country.
High political office is a club, and the members look after one another.
Nevertheless, Musharraf is being greatly inconvenienced by the trial, and last week the Taliban nearly got him with a roadside bomb near Islamabad.
Doubtless he missed Pakistan, but what bizarre calculation could have led him to go home and put himself in the hands of his many enemies?
Musharraf said he was coming home to run in the 2013 election, which was delusional in the extreme.
There was little reason to believe that many Pakistanis would want to vote for him after living under his arbitrary rule for eight years.
There was no reason at all to think that he would not be disqualified from running in the election and put on trial for grave crimes.
Yet Musharraf is not alone.
Other ex-dictators, far nastier than him, have succumbed to the same delusion and gone home convinced that they would be welcomed back.
Another recent case is Jean-Claude ''Baby Doc'' Duvalier, who took over as Haiti's dictator at 19 when his father ''Papa Doc'' died in 1971 and ruled it until he was overthrown by a popular revolt in 1986.
Haiti was the poorest country in the western hemisphere when he took power, and still the poorest when he lost it, but he took an alleged $120 million with him into exile in France.
His dreaded Tonton Macoute militia murdered thousands and drove hundreds of thousands into exile, and many of them were massacred in the revolution that ended his rule, but he lived on in Paris in great luxury.
Eventually, Duvalier's spendthrift ways and an expensive divorce got him into financial difficulties, but just going back to Haiti was not going to fix that.
Yet he went home in 2011, after a quarter-century in exile.
He said he was ''just coming to help'', whatever that meant, but he arrived just as the recently elected president was facing charges of election-rigging, which led some to speculate that Duvalier still had political ambitions.
He was arrested and charged with embezzlement, human rights abuses, and crimes against humanity.
Three years later the courts are still pursuing him on those charges, but in the meantime he is frequently seen lunching in the bistros of Petionville, and has even been welcomed at the same events as the current president, Michel Martelly.
It's safe to say that he will not die in jail.
Two things are odd about this phenomenon of ex-dictators confidently returning to the scene of the crime.
One, obviously, is their belief that they are still loved (as if they ever really were).
But that is less strange than it seems, for during their time in power very few people dared to tell them anything else.
What's much more curious is the fact the countries they misruled eventually find it necessary to forgive them.
They do this not so much out of sympathy for the man who committed the crimes, but rather out of a need for the nation's history not to be merely a meaningless catalogue of blunders and misdeeds.
Musharraf may have come back a bit too early to benefit from instant forgiveness, for some of the people he hurt have not yet retired.
But he will not face really serious jail time or the death penalty, because Pakistan's army would not permit it.
And he will be forgiven by Pakistan's historians and myth-makers in the end, because somehow or other the history has to make sense.
• Gwynne Dyer is an independent London journalist.
