I have heard enough whining from the Bernie Bots about the Democratic primary process being rigged against him.
Of course it is rigged. It is rigged in favor of Democrats. The people who are active in the primary process, particularly in caucus States, are most all life-long Democrats, who have always been loyal to the Democratic party. So is Hillary. Bernie is not. He has spent his life refusing to join the Democratic party, only now grudgingly participating in Democratic primary contests, while still clinging to the title of independent. Does he expect a reward for that? Does he expect the party's loyalists to not favor other party loyalists, and extract a price from him for not being one?
After all, these are the Democratic primaries, intended to pick a candidate for the Democratic party, not the Democratic party and whichever independents want in on the show this year. Bernie has never demonstrated enough loyalty to the Democrats to officially join them, even now; why should they reward him now?