I went down that rabbit hole years ago!
I was SO fascinated by her psychology. The pretense actually extended/extends beyond 1 or 2 tales told to the press. She's named her kids Spanish names, frequently talks/posts about her Spanish childhood (born and raised in Boston her whole life, 2 professional very American parents in high-flying corporate & academia), speaks in a Spanish accent 24/7 and pretends not to know simple English words frequently.
Or at least did before she was uncovered (though she doubled down for the LONGEST time, even after articles mocking her came out eg front page of NY Post with her in a matador costume). Not sure if she still lays it on that thick
She attended NYU, so she claims to have newly arrived in the US, wide-eyed and starry-eyed from Spain at 18. Seems to have modelled herself after Salma Hayek who purportedly rejected Alec Baldwin. IIRC she (Hilllary) also did the Meghan Markle thing of pretending she didn't know who Alec Baldwin was when they met, as apparently her family didn't have a TV in Spain.
Americans also don't really know where Spain is / who Spaniards are (to them Spanish = Hispanic/Mexican, whereas actually a great deal of Spaniards look pretty white, and Spain being a first world country, most Spaniards are economically stable). So most of her shtick was talking about being a dark-skinned poor immigrant, and most of the American public also got their knickers in a twist that she's appropriating "poorer minorities".
Sorry for the wall of text! I'm not that interested now, but when I was fascinated, it was sad because the only other people deeply interested are batshit insane. They're still on the Hilaria Baldwin subreddit and they do things like deface her children, photoshop her into sexual positions etc (though tbf sometimes she asks for it, like forcing minimum wage workers in her house to pose as props in her sexy gymnast poses, or twisting herself into sex poses while sitting in pots/pans – yeah I don't understand either).
But they go way beyond logic and reason. I think their deep seated hatred of her is prob just schadenfreude at watching a privileged WASP's downfall. Many seemed not to have jobs either from the way they would literally post every few mins/hours from morning till night?!?! Anyway, sad, I really wanted to know why she did it, and there are actually some fascinating clues!