No credible US poll reports that President Donald Trump has the support of 750 million people, a number far exceeding the US population.
A US poll found that President Donald Trump has the support of 750 million people.

New Marquette Law School Poll national survey finds public strongly favors some Trump policies, strongly opposes others // News Center // Marquette University
Source: marquette.edu
Key Evidence
The US population is about 330 million, so 750 million supporters in a US poll is impossible.
Multiple polls from reliable sources show Trump's approval ratings are below majority support.
No credible polling data or news sources report any such figure anywhere in the world.
What the Evidence Shows
The claim that a US poll found President Donald Trump has the support of 750 million people is factually incorrect. The total population of the United States is approximately 330 million, making it impossible for any US poll to reflect support from 750 million individuals. None of the provided sources mention any figure remotely close to this number.
Instead, multiple reputable polls indicate that Trump's approval ratings are below majority levels, with many Americans disapproving of his job performance and policies.umass.eduumass.eduNew National UMass Amherst Poll Finds More than Half of Americans Disapprove of... Furthermore, international polls show low confidence in Trump's leadership globally, and domestic surveys reveal mixed or negative public opinion on his agenda.
marquette.edumarquette.eduNew Marquette Law School Poll national survey finds public strongly favors some...+5 more
The figure of 750 million likely stems from a misunderstanding or deliberate exaggeration, as it exceeds not only the US population but also the population of any single country. Therefore, this claim is demonstrably false based on demographic facts and polling data.