Presumably, Hillary won the popular vote in 2016. But I think the reality is a good chunk of Democrats don't like her. A friend of mine was a Bernie supporter, but when he lost, she did not vote for Hillary. "Can't stand that *bleep*," she said. I think my friend wrote in Bernie for the general election. Hillary just rubs people the wrong way.
Given her health, she would be a fool to run again. Just stay home, Hillary. Play with your grandchildren. Hold fundraisers. Groom your kid for a political career. But give up running for president yourself. You aren't wanted.