That's what screenwriter Jeff Greenfield, writing for Politico, says:
Celebrations of the Fourth do not tend to benefit both parties equally, and here, Trump may well be demonstrating his instinctive grasp of which way a big event tends to nudge the populace. In 2011, two academics who studied the political effect of Fourth of July festivities concluded that: "Fourth of July celebrations in the United States shape the nation's political landscape by forming beliefs and increasing participation, primarily in favor of the Republican Party. … The political right has been more successful in appropriating American patriotism and its symbols during the 20th century, [so] there is a political congruence between the patriotism promoted on Fourth of July and the values associated with the Republican Party.”
For all that, history also suggests there's good reason that his plan is rubbing people the wrong way. For one, it really is rare; it's far more common for presidents to vacate Washington on the Fourth of July, or to remain at the White House, than to insert themselves into the proceedings.
Someone who can say of himself that he has been treated worse than any president in history—four of whom were assassinated—has an impressively unique understanding of his own role in the American story, to say the least.
NPR says the event will cost taxpayers millions. And Rick Atkinson takes a broader view, comparing us on our 243rd anniversary of independence from Britain to Britain of that time.