Dem primaries aren't "rigged" precisely, but there is a payoff in not just appealing to "voters" in some broad sense, but in getting the support of various influential people who, through their influence, try to help you get support! That's sort of a normal part of politics which is not new and which we all understand. Get the local leaders, the union leaders, the various community leaders, the issue leaders, etc. Gather those endorsements. I think a trickier bit is that "influential people" now also includes various people who are paid to opine on TV, not precisely in an objective sense, but in a not being totally explicit about their sympathies sense. Especially with the revolving door aspect...from teevee to the White House and back again.
I'm not saying this is corrupt, just that it is a thing which is fair to observe and point out. People are making career bets.
