That's actually quite interesting from an electoral perspective, as firefighters are the sorts of peeps that Trump depends on.
As to Vance, he's been living inside the Republican bubble.
Now he has discovered that in the world outside, he and his type are loathed by many. And he hasn't got whatever it is Republicans like about Trump to compensate. He just comes across as a hateful human being, especially towards women.
To be fair to him, there was one thing he said about post-menopausal grandmothers and their role in support of children, which, while politically toxic and somewhat hateful, has something of a justification in science, insofar as they think grandmother orcas play a similar role and it is justified as an evolutionary survival mechanism. Not only that, but a lot of grandmothers enjoy providing that sort of support. But Vance puts his case in such an obnoxious way that nothing of the value of grandmothering survives it.