People always lose office. It's how it works. Look at who's in charge now. You think they're anti-establishment?
What Labour are and what they do proves nothing about the establishment. It's an issue in its own right, yes. The way you're talking it's as if people haven't always voted parties in and out of power because they like them or don't.
And if you want it that way Corbyn was much less of an establishment man than Johnson and he had his arse handed to him. Not that he got a majority of the vote, but Johnson has persuaded people to vote for a bunch of Oxbridge educated elite in the name of changing things. It'd be hilarious if it wasn't so serious.