You've had two seasons of assistants telling her that she's been fucking up dealing with Elliot, so for her to let herself get in so over her head when she's been in control for most of the show seems crazy uncharacteristic.
It all boils down to if the sci-fi herring is real; because her overwhelming zealotry is the only thing that can explain at how every given sign she was given to slow down she pushed on.
Several of her assistants have correctly pointed out that Elliot was her one biggest weakness, and if it wasn't for Elliot basically coming through in the clutch and giving WR what she wanted with a hack to get her project shipped to the Congo, Elliot & Darlene would've been dead in that barn.
Elliot spent months going underground, working his few leads to try and find where WR was most vulnerable. From the beginning of the show, Elliot/MR has always said that the top 1% of the top 1%'s power comes from money. Elliot just hadn't made the connection that WR & the DA's power all stems from this vast collection of wealth.
I also take this all as a massive sign that WR grew overly-confident as her objective was nearly complete, especially after how she managed to basically decimate f.society in S3 (rip Trenton/Mobly) and almost killed Darlene & Elliot too. Elliot proved in S3 that he can hack & be one step ahead of the dark-army when he puts his focus on them; its literally how he saved himself and Darlene.
Sure, Elliot got the backstory on Deus group relatively recently in this plot, but where he was aiming (hacking Cyprus bank to steal WR's funds) wound up still being the end-goal of the hack; now he just knew who exactly he was stealing from beyond just WR.
Whiterose has always seemed to me as someone who prides in her control, but does struggles with it. There were various examples in S2 & S3 where she received bad news by destroying things around her. Heck, if you look at the story of Mr. Robot from her point of view (allowing a group of hackers to hack one of the biggest members of the Deus group in order break the US public's trust in this banking empire enough so that a new form of crypto-currency that the Deus group primarily controlled, as well as allowing China to annex the Congo all so her project could be safely shipped there), then WR's entire plan can be seen as a massive risk that relies on a successful hack that she didn't even want to go through with at first (DA denied F.society several times in S1).
There could've been other ways WR could've gotten what she wanted. But go back to her outbursts that caused her to lose control and break things around her - WR tends to lose her cool and control whenever she needs to wait for things. This actually comes up several times with her (the timeliness, ensuring phase 2 happened because she "had to ask twice", sparing Elliot because he created a hack that would get her project shipped to the Congo faster). Its actually a point that they spend half an episode this season elaborating on when she tells her assistant "i'm tired of waiting", when she ultimately ignores the assistant's pleas to cancel the Deus meeting because there were too many unknown variables at play, including Elliot.
Whether Elliot knew it or not, he took advantage of a weakness of hers, big time.