I really like Elizabeth Warren. She's right about the need to fix the process by which we pick political leaders. I have No disagreement that the process is biased toward people who have been in power for a while. No disagreement that elections are heavily influenced toward a few big donors/lobbyists/well funded PACs. So, it comes down to what is meant by "rigged".
Clinton had a heavy advantage over Bernie because she had been working as a politician for something like 20 years. Reaching out, talking to anybody who would talk with her. Sticking her neck out on controversial issues. She made some enemies but many more allies and that is why she beat Bernie. She worked for it and played by the rules at the time. Did she have too much of an advantage over Bernie? I don't think so. Bernie was a terrible politician. Said dumb things about Black people, did not reach out to people who questioned him and in fact he was a big nothing in Congress. A senator for 12 years with nothing to show for his time except a changed name on a post office? Really? That's your guy?
Yet, Sanders did look to beat Clinton for a while there. His problem was the he had zero credibility with Democratic voters in the South. He lost every primary election there. So here it is again. White Bernie Babies are disregarding Black people and their concerns. We saw their racial bias when they complained about "people not voting in their own self interest", even some Bernie Bro opinion pieces calling them ignorant.
So, if Warren says the election was rigged because the system is biased toward entrenched politicians, then that's a positive way to look at the problem. If you are saying the election was rigged because a nobody politician was at a disadvantage when running against an experienced one. Yes, Bernie was at a disadvatage when he ran against a hard working and canny Hillary. By demanding a level field between two politicians with such disparity in their records, you are just demanding free stuff. That's a common complaint I've heard about Bernie's bros.
Elections are hard to win. They are meant to be hard to win. You have to work for it. Sorry, the presidency will not be given to Bernie because a tiny fraction of the Democratic Party likes him. Not sorry.
Going back to what the head of the DNC said, including what she said in her book:
Brazile: I found no evidence Democratic primary was rigged
If you read it, you'd find she was most upset about the DNC being shuffled aside after Clinton bailed them out because they wasted a ton of money on "consultants". She makes some good points. But Clinton's team was right about that.