Warren might well believe she can become the nominee at a brokered convention.
Under it all, though, is a hardline ideological opposition to ending neoliberal policy, and ending capital-led, market "solutions" to public policy problems.
Buttigieg articulated this extreme distaste for what Sanders represents well with his lines about "burning our Party down" and "the revolutionary politics of the sixties" … with all the unsustainable bad logic partisan opposition to historical achievements like those of the civil rights movement entails.