Ten tourists dead in Istanbul, with 15 others wounded: another dirt-cheap win for the Islamic State. The body count may be low by the standards of neighboring Syria, but the end result of this suicide bombing in the world’s most intriguing city will be months, if not years, of damage.

Despite President Obama’s self-congratulatory rhetoric on terror, Islamist fanatics have proven to be inspired, innovative, resilient and committed to their purpose unto death. And in at least one sphere, we’re losing big.

Islamist terrorists have made our world smaller and narrower, crippling travel and destroying tourism in countries that depend on it for revenue. Their campaign to break the economies of Muslim states by discouraging “infidel” visitors already has crippled Tunisia and Egypt for resisting the thrall of fanaticism. Jordan’s hurting, too.

Tuesday, it was Turkey’s turn. Why? Because Turkish President Recep Tayyip Erdogan had, at last, cracked down on foreign recruits for ISIS transiting Turkish territory.

He also had, reluctantly, shut down most of the illicit cross-border trade with the Islamic State caliphate — 21st-century caravan routes that had allowed Islamist fanatics to thrive. Already in a spat with Vladimir Putin that halted Russian package tours, Erdogan now faces the loss of income from better-heeled Western travelers.

“Tourist-cleansing” is becoming one of Islamist terror’s most effective techniques of state subversion.

And it’s not only hurting Muslim populations. Last autumn’s horrific Paris attacks made potential visitors think twice. Whether plodding about Istanbul’s historic Sultanahmet district with selfie sticks or lounging on a Tunisian beach, tourists are the softest of soft targets.

Driven by necessity, our Islamist foes have developed a genius for making war on the cheap. The Obama administration has tried to make war on the cheap with Western arms, only to find it very, very expensive. For a few thousand dollars — or less — terrorists cripple a troubled state’s economy. We spend a million dollars to take out a pickup truck.

We continue to underestimate both the dimensions of the threat and the creativity of our enemies. President Obama’s latest ploy has been to downplay the danger yet again, to insist that we shouldn’t over-react to terrorism — which his underlings blithely dismiss as “not an existential threat.”

Yet we live in a world in which even boarding an aircraft is humiliating. A world where entire countries and regions have become no-go zones for the average traveler. A world in which Islamist barbarians have greater freedom of action than ever before, while civilized men and women can no longer visit the Pyramids with confidence.

For me, as a lifelong, enthusiastic traveler, Tuesday’s Istanbul attack got personal. I have great affection for the city, which I first experienced as a backpacking sergeant on leave in 1979. The city was poor and gray that year, and rough-edged with partisan strife. But it was magic — its Byzantine and Ottoman monuments incomparable, its hospitality threadbare but seductive, its alleys full of secrets.

Since then, the city has prospered and swelled, but its historic heart — where the suicide bomber struck — still has the greatest concentration of religious and secular architecture in the world, from the Blue Mosque to the Topkapi Palace, along with the secularized Hagia Sophia, the Church of the Holy Wisdom, which is the most important construction of the first Christian millennium.

‘Tourist-cleansing’ is becoming one of Islamist terror’s most effective techniques of state subversion.

And those are just the big three: There’s a Byzantine race track, Ottoman baths and ghosts around every corner.

The terrorists want to deny us access to all of it. Given the chance, they’d destroy Hagia Sophia and all the palaces. They want to erase history, to cancel civilization, to inflict the rule of a grisly tribal god — not the Allah of Islam’s glory years — on all humanity.

The terrorists won’t succeed in that ultimate goal. But they’ve already made the world an uglier place.

They’ve terrorized cities from Brussels to Mumbai. They’ve destroyed hundreds of thousands, if not millions, of jobs in struggling states and killed even more dreams than they’ve killed men and women.

And our president claims that we’re winning.

Ralph Peters is Fox News strategic analyst and the author, most recently, of “Valley of the Shadow.”