Easy to say. Following through would be much more difficult for Donald Trump, especially domestically.

Trump's frustration is easily understood. America's allies outside of the Gulf states have turned out to be fair-weather friends indeed. The US played Europe's appeasement game with Iran for two decades after the exposure of Tehran's nuclear-weapons program, not to mention 47 years of terrorism around the world. When we estimated that the mullahs were days away from nuclear weapons, Trump took action with Israel to end the threat. Months later, the Iranians still refused to negotiate seriously on any of the threats they posed, and then massacred tens of thousands of unarmed citizens in the streets. Trump spent seven weeks attempting negotiations again, at which Iran balked again.

Europe has not lifted a finger to provide any substantive assistance, not even a diplomatic effort, other than at NATO itself. The US has fought to clear Iran's grip on the Strait of Hormuz to allow the free flow of oil and liquified natural gas (LNG), almost none of which comes to the US but much of which flows to Europe. Trump has always spoken skeptically of the partnerships with EU/NATO allies, and this morning, he finally vented on Truth Social that they could open the Strait of Hormuz themselves and "go get your own oil":

All of those countries that can’t get jet fuel because of the Strait of Hormuz, like the United Kingdom, which refused to get involved in the decapitation of Iran, I have a suggestion for you: Number 1, buy from the U.S., we have plenty, and Number 2, build up some delayed courage, go to the Strait, and just TAKE IT. You’ll have to start learning how to fight for yourself, the U.S.A. won’t be there to help you anymore, just like you weren’t there for us. Iran has been, essentially, decimated. The hard part is done. Go get your own oil! President DJT

This confirms reporting by the Wall Street Journal last night that Trump has told aides that he might not worry about reopening the Strait of Hormuz:

President Trump told aides he’s willing to end the U.S. military campaign against Iran even if the Strait of Hormuz remains largely closed, administration officials said, likely extending Tehran’s firm grip on the waterway and leaving a complex operation to reopen it for a later date.

In recent days, Trump and his aides assessed that a mission to pry open the chokepoint would push the conflict beyond his timeline of four to six weeks. He decided that the U.S. should achieve its main goals of hobbling Iran’s navy and its missile stocks and wind down current hostilities while pressuring Tehran diplomatically to resume the free flow of trade. If that fails, Washington would press allies in Europe and the Gulf to take the lead on reopening the strait, the officials said. 

There are also military options the president could decide on, but they aren’t his immediate priority, they said.

Again, this is more easily said than done. There are several reasons why Trump can't afford to leave the Strait to Europe or anyone else. In no particular order:

We opened Pandora's Box in the Strait with this war on Iran. The only real way to close it again is to seize control of the Strait and force Iran to capitulate. Regime change would likely follow and solve the rest of these issues, but leaving the regime in charge of the Strait and "taxing" tankers for passage will only keep the regime remnants more firmly ensconced. Let's hope that Trump wants to be taken seriously rather than literally with his social-media post today.