The loss in SC is indicative to why Bernie is struggling, at least in the south. Bernie is the more popular candidate with people under 30. Older voters are with Hillary. Two things jumped out during that primary.
1. Of the registered voters under 30, only 13% showed up to vote. Bernie can have thousands of people at his rallies and people can donate til they are broke. But if they don't vote it means squat.
2. The local news interviewed some voters exiting the polls and some at the HRC victory speech. Various ages, couple of men but mostly women, all African-American. They were happy for Hillary of course and excited about her going forward. When asked what they knew about Bernie Sanders, they looked at each other and one of the women said "nothing."
They don't know who he is, much less what his policies are for this election. Is it Bernie's fault? Surely not, but he might have been able to get his foot in if he spent more time there? I don't know. Is it their fault? Maybe, but it doesn't make any difference. Bottom line is those voters were set on Hillary because her message to African-American voters in the south is to continue the momentum Barrack Obama has established. Hillary knows where her bread is buttered with southern African-American voters. That trend will probably continue through super Tuesday.
People just aren't voting. And the media builds results up as "A huge landslide... the people have spoken in SC!" Well, 13% of the people have spoken.