I find it bemusing that people don't think a forty-year politician is part of the "establishment." 
Add that to the fact that the first female Presidential candidate - and, truly, ANY female politician - doesn't have the option to not court the establishment, and I find this argument petty and tiresome. 

Sanders has been making $200K a year for decades. He's not rich because he frittered it away on who knows what. He hasn't ever had a "real" job that I know about. That's privilege. That's establishment. That people are going after Hillary for actually leveraging her income into wealth is a double standard that represents the moving goalposts every ambitious woman must face.