So, her campaign failed due to optics:
"Besides the misallocation of resources, many felt they had turned a candidate known for her tough-minded, blunt-spoken approach to politics into a more conventional politician. The portrayal of Warren primarily as a candidate of competence — “Warren has a plan for that” became a signature rallying cry — was not true to the candidate’s strongest selling points."
And don't forget that she is a victim of 'sexism':
"Nearly all the officials, who spoke on the condition of anonymity in order to share their insights candidly, cited the double standard Warren faced on the campaign trail. When she went on the offensive, the backlash was usually more severe than it was for her male rivals, they said. And her bar for overcoming gaffes and misstatements, they believe, was much higher."
https://www.politico.com/news/2020/03/06/warren-team-wonders-how-they-blew-it-122628