As the Donald Trump phenomenon endures, it’s become fashionable to make a certain kind of excuse for the boorishness of his backers, if not The Donald himself.

“Don’t blame them” is the theme of front-page stories and much-discussed magazine essays. The economy left them behind, the world doesn’t work like they were promised it would as young people, and we have to understand. They’re angry, and should be.

Well, bull.

I have the unfair advantage of being a near-demographic match for Trump’s core voters. According to the Hoover Institution at Stanford, half are ages 45-64 and another third are senior citizens. They’re concentrated in the middle to lower-middle of the economic spectrum — slightly more likely to report $50,000 or lower annual incomes, a bit less likely to earn over $100,000. That was more my dad than me; he lost his dockworker father early and was raised by an immigrant widow who rented out rooms to get by.

And here’s the difference: I didn’t drop out of school after high school.

“ If you ask how much sympathy Trump voters deserve for failing to deduce, or act upon, what my father and millions like him did 53 years ago, the answer has to be: not much. ”

Of all the reasons not to waste tears on Trump’s supporters, the best is that they ignored clues that couldn’t have been more obvious if you were there. Put bluntly, if you’re 45-plus and thinking life passed you by because you didn’t understand the necessity of an education any time after 1975, you were too hormone-addled at 18 to grasp something that had long been obvious.

When Trump’s base was coming of age, John Naisbitt’s “Megatrends” was a best-seller for a full two years. You couldn’t read it or even hear about it much (and it spawned dozens of books and too many articles and TV segments to count) without understanding factories were closing and not coming back, and people who grew up wanting that life needed a Plan B. The 1982 recession, which launched Barack Obama’s career as a community organizer in neighborhoods hit by steel-mill closings, made it pretty obvious too. (Cue Bruce Springsteen: “Foreman says ‘these jobs are goin’, boys/and they ain’t comin’ back.’ ’’)

Naisbitt couldn’t have made it much simpler than he did: “Farmer, Laborer, Clerk: That’s a brief history of the United States.” And the part where laborer was the most common, secure occupation, he said, was over.

I certainly understood that when I left high school in 1979 — it was simple. And spare me the “he’s elitist-liberal-media” song: I was born in a fully deindustrializing Jersey City. Dad sold real estate, two uncles were cops. I went to a non-elite university and paid for it myself. I won’t forget my college introduction: The girl from financial aid exclaiming in front of a long registration line: “Wow, you get everything!”

But you could even see it in 1962, when my parents got us out of Jersey City as thousands of others did. Dad overrode my mother, insisting on a suburb where college was taken so much for granted that none of us would buck it. Instead of growing up at the shore, as Mom wanted, we went someplace where all but the biggest stoners did college.

If that meant very cheap county colleges, you did that. Everyone could. Still can: The average state college costs $9,100 a year before financial aid, and community colleges cost $3,347, according to the American Association of Community Colleges.

If you went to even a modest college then, the payoffs have been lifelong. Median real wages of college graduates rose 23% from 1979 to 2009. Median real wages of high school grads have fallen 12%. Drop out of high school, and you make 23% less than in 1979. By that standard, $3,347 is cheap.

So if you ask how much sympathy Trump voters deserve for failing to deduce, or act upon, what my father and millions like him did 53 years ago, the answer has to be: not much.

That’s especially true if that voter responds to stagnating wages by braying about illegal immigration when the number of undocumented immigrants has been stable for years; carping about a supposedly recent “war on coal” when coal employment has fallen since Ronald Reagan’s administration; or prattling on about criminal tendencies of Muslims, Mexicans or blacks. If it feels like no one is on Trump voters’ side, well, nobody likes a sore loser.

Vince Mullaney, who died in 2003, liked Trump: They shared brashness, conservative bias and disinclination for time-wasting research. (Unlike Trump, Vince could, usually, take a joke.) But he’d understand Trump’s loudest backers are folks who lacked his own smarts, work ethic and willingness to “disrupt” his own life to do what our family needed. Pressed, he’d agree they should’ve gotten off their rear ends when they had the chance.