See, here’s where you’re missing the point: those guys in those shirts thought that the country worked like that for them all along. And for many of them, it did. And now that the “others” — racial minorities, gays, women, etc — are using the rules of our country to push back against what they thought it was, they’re wanting to change the rules of the country to protect their place in it.
(please note that by “the rules” I’m not merely referring to legal documents, but also the unspoken/unwritten rules of polite society and the social contracts of our communities)