Kaiser Wilhelm is on the road again, hanging with his peeps in Hamburg and waxing nostalgic for the glory days — when all the cool kids lived on the east side of the Wall and the socialist revolution was always just over the horizon.

OK, just goofing about the waxing-nostalgic part, but really: When the mayor of the capital city of global capitalism hops a plane to protest the G-20 meeting now underway in Germany, it’s not unreasonable to wonder: Will he be wearing a Guy Fawkes mask today — or his Che Guevara T-shirt?

Didn’t he honeymoon in Havana, after all? Why yes he did!

No need to speculate about this much, though: Bill de Blasio, nee Warren Wilhelm Jr., happily will fly 3,807 miles to weep for the world. But he doesn’t give a damn about you.

He doesn’t care about you so profoundly that he won’t even pretend to care about you.

So as you start your workweek Monday by stepping around the subway junkies, and all the other de Blasio Administration platform detritus, your mayor will be sleeping off jet-lag from his latest silly effort to make himself a player with the international hard left.

Then there’ll be the ritual two-SUV jaunt to his Park Slope gym and then — maybe, if there’s time — a spot of work before lunch.

It’s good to be the Kaiser.

Especially a lucky Kaiser.

It really is true that a rising tide lifts all boats, and no boat has been hoisted higher than de Blasio’s by New York’s astonishing post-2008 economic expansion. The slow-motion foreign-cash tsunami that swept over the city during Mike Bloomberg’s latter years endures — guaranteeing de Blasio dough to buy labor peace and arming him with the big bucks needed to keep the city’s legion of special-interest pleaders at bay.

Consider this: The only City Hall demonstrations these days are staged by anti-cop cranks and other on-the-margin crazies. Everybody else is well-fed and relatively happy — and certainly not about to agitate for a new mayor, who might derail the gravy train.

This is why de Blasio, in his re-election year, sees no real opposition.

Lucky for Kaiser Wilhelm. Not so lucky for New York.

For while the city has no pressing need for cash right now, it desperately needs leadership — political and policy leadership of the morale-bolstering sort provided so emphatically by other mayors, in earlier times.

Think Ed Koch, after the fiscal crises. Think Rudy Giuliani, during the street-crime epidemic and as the Twin Towers fell. Think Mike Bloomberg, on the long road back from 9/11 and beyond.

More to the point, think Koch on the Brooklyn Bridge on the first day of the 1980 subway strike — taking symbolic custody of a calamity not of his making, but one which sorely required a visible leader.

Then, as today, responsibility for crisis in the subways was with Albany.

Then, the mayor stood tall — and Albany noticed. Today, the mayor is in Hamburg — and Albany could not possibly care less. He’s certainly done nothing yet to make Gov. Cuomo pay a political price for his dilatory approach to mass transit — and there’s no reason to believe he will in the future.

So suffer your “Summer of Hell” alone, New Yorkers. Obviously, City Hall doesn’t care.

It is almost inconceivable that de Blasio would miss Monday’s wake for martyred NYPD officer Miosotis Familia: That is, inconceivable because the mayor’s perpetually troubled relationship with his police force couldn’t survive such an insult — but almost, because let’s face it: The Kaiser is capable of anything.

Except coherent leadership.

Today he’s feeding his Fidelista fantasies in Hamburg. Before that it was in Atlanta; and before that, in Iowa (and long before that, in Nicaragua). Nobody paid attention, except for those who just laughed at him.

Now the real joke is on New York City, where de Blasio is sleep-walking to a second term — where everything will be fine and dandy just so as long as the cash holds out.

Can the Kaiser be that lucky?

Bob McManus is a contributing editor to the Manhattan Institute’s City Journal.