You could have said that 50 years ago, but now what was true of "Ivy League WASPs in the Northeast" is true of many well-off suburbanites all across the country. And that accounts for a lot of what's happening in this election.
On the other hand, Irish-Americans are, next to the Jews, the most leftist white subgroup. Both Irish and Jewish people have long memories and grudges. They project crimes committed against their kinsmen on the other side of the Atlantic onto traditional American society.
The Irish are a swing vote. Remember Reagan going to Irish bars in very Tip O'Neill Democrat Massachusetts? Some of the people there voted for him, I'm sure.
The Irish vote is divided by age and class. In much of the country suburbanites of Irish ancestry aren't so different from those Ivy League Northeast WASPs. In fact, they sort of are the new WASPs, especially the younger well-off Irish-Americans. Less affluent Irish-Americans don't vote the same way. Older ones are also less reliable votes for the Democrats, depending on where they live.