My opinion is that as she looks at the polls and sees spoilers in the race taking votes away from Biden, putting Trump in the lead, she will panic and strongly think that someone must enter the race who would actually take votes away from Trump. She promised she would do whatever it takes to stop Trump. Running as an independent probably would do very little to accomplish that but, if she were to get the nomination for the Libertarian party, it could very well give them the strongest candidate they ever had and take votes away from Trump as most Libertarians do anyway. Not so far fetched but, even then, she may take away votes evenly from both Trump and Biden.