I don't understand what Warren supporters get out of this election. She's behind Bernie in every state, and Bernie's margins would like be larger in super Tuesday states if she wasn't running.
That is not guaranteed. Bernie is second choice for maybe a 1/3 of Warren voters, with the rest split between the other moderates. And even if Bernie is pulling more voters than say Biden from Warren supporters, there's always a risk that some that might have gone to say Buttigieg could go to Biden if he seems more viable.