Why ethnic minority voters preferred Hillary Clinton over Bernie Sanders?

[Del Tachi]

Black voters in the South maintain an effective "veto" over the Democratic nomination process because of DNC delegate allocation rules that make Southern states relatively delegate-heavy.  No Democrat has won the nomination without securing the bulk of Southern Black's support - not Hillary, not Kerry, not Gore, not Bill, etc.  In that sense, Hillary was very smart to tailor her message and campaign to Southern Blacks.

To answer the broader question, Black Democrats (especially in the South) see themselves as much more the beneficiary of activist government than White Democrats.  For this reason, there is a propensity for Southern Blacks to gravitate towards more pragmatic, electable candidates because they have too much to lose by supporting an ideologue like Bernie Sanders.  White liberals don't have the same skin in the game, so to speak.