OK that didn't work so who else you got? Bernie, outsider with nothing, no money, no establishment friends, too old, been a democtat for 5 minutes and nearly got the democratic nomination and the dem establishment hate him and broke the rules fighting him. Donald has fame and got the republican nomination. Republican establishment hate him.
American voters want change. Change at any cost right now. And they'll keep trying for it.
There has been no meaningful political reform. Regulatory capture and gerrymander are the norm. People hate it. They genuinely hate the status quo, the political establishment. Really hate it.
Whoever is judged the most likely to do something, anything, in the way of reform has a huge advantage. You can be inexperienced and African American, you can be a blow-hard who inherited a billion dollars. Doesn't matter if people actually believe you are more for change and reform than the opposition.
It's not the only important thing but having credibility as an agent for change is extremely valuable. Hilary had precisely no credibility on that count and was proud of it .