She (and everyone who enabled her) crossed every barrier laid out to impede them. They knew they were breaking the law, but laws only hold weight when they're enforced. So for each barrier they crossed, each person who stepped aside and allowed them to continue, they became more emboldened. Maybe those who enabled the mob didn't see it as much of a threat. Maybe they secretly agreed with them, or maybe they got some personal gain from letting them continue. Regardless of why, she and the mob were as surprised as the rest of us to find themselves wandering the seat of our nation's power, almost entirely unopposed.
Then they came across yet another barricade. Behind that barricade was a secret service agent, weapon drawn in an alamo position, presumably tasked with protecting the leaders within the building - almost the entire line of succession to our republic. He, like all the others before him, was ordering them not to cross the barricade. It's difficult to imagine a more clear and present danger to find yourself in as an American citizen - staring down the barrel of a secret service agent while trespassing in the Capitol. (It has been pointed out that it was a plain-clothsed Capitol Police officer, ostensibly acting in the same role as a secret service agent but for the Legislators. Original left for clarity). Surely she, a 14 year veteran of the Air Force can be expected to know the danger she was in. But the frenzy, the empowerment , and the reinforcement they got by crossing all of the lines behind them led her to believe that even this was a line she could cross. It wasn't until she was shot that anyone else in the mob even stopped to consider the danger they were in.
Had she not been killed, they would have continued to do whatever they could get away with.
If that isn't the personification of Trump and the MAGA cult, I don't know what is.
Edit: I wanted to add some additional context since this blew up, in case my attempt at being brief muddied the point I was hoping to make:
Never before in our history has a President been so emboldened to circumvent the law in such a brazen manor. The events of this week are not simply the delusions of a senile old man. For the past 5 years, and likely much of his life, Trump has gotten away with doing whatever suits his fancy. Our nation, and it's leadership have enabled him throughout his tenure, whether by blind loyalty or for personal gain. He has been let off from an impeachment, with no lasting consequence. Didn't even have to testify. He has been allowed to lie to the American people, again and again from the highest office in the land, but that barrier carried no weight either. He suppressed the vote, tampered with the postal service, used the office for personal and professional gain, and destroyed the citizenry's faith in our electoral system. So far, all barriers crossed with little to no resistance. We cannot expect Trump to simply stop pulling the levers of power of his own volition. Even when he eventually moves on, the blueprint for his scheme is publicly available, and someone else will fill the power vacuum. Likely, someone with more subtlety, and common sense. Someone much more difficult to oppose, or indict.
A bigger threat to our democracy we haven't seen since the civil war. But, pretending this issue just goes away with Trump... to treat his agenda, his methods as an outlier now that they've seen popular support is foolishness. If we as a nation don't establish his treason, sedition, and attempted coup d'etat as the barricade that can never be crossed, if he and his enablers escape this mess without repercussion, we have only ourselves to blame when he or the next demagogue like him crosses that line.
And, watching the rioters being escorted peacefully down the steps of our Capitol, I fear we'll make the same mistake.