It's either a failure of the existing elites – such as the media and the current parties who have failed to heed people's concerns, or it's the fault of the people, who can then be vilified
Kind'a. It is the former, but the situation is significantly more complex.
In a country with real working and middle class in long term employment populism does not work. There is nothing for a populist to attract the vote. One can argue a populist cause, but everyone will evaluate the cause versus their future and tell him to f*** off.
This is no longer the case. There is no more working class in long term employment. There are dispossessed deplorables instead. The middle class is reduced to a fraction of its former self and is no longer in long term employment. THAT is the handywork of the elite you refer to. There is nobody beating the workforce mobility drum like the Wall Street and the City. It is a Wall Street and City religion. This changes the situation - you suddenly have huge social strata which has nothing better in the future. The only change they can experience is for worse. Are they going to be a rich fertile ground for a populist politician? Of course they will. This is what Trump, Farage and Co leveraged so effectively. This is also the background versus which the people who were first to congratulate them are working to achieve the same. Austrian Freedom Party - calls from Corinthia where the unemployment is 20%+ and a large portion of the population has joined the deplorables. Orban and Co - similar story. Le Pen draws most of her support from similar sources. And so on.
So actually, if we look at this election the only person right on the money was Bernie. Historically, only socialists have been successful in countering populism from the inside in open elections. All other populist successes (though we usually refer to them as nazi, fascist, etc) were destroyed by outside forces. Liberal bourgeoisie politics stood no chance. When the social situation becomes fertile for populism, bourgeoisie loses. So based on lessons from history Hillary was doomed from the start. The only choice Democrats ever had was Bernie.
So coming back to the elite vs the people. If we are to prevent repetitions of Trump, Farage, etc in the long run the only way is to take the next Silly Valley/Wall Stree/City oligarch sprouting about workforce agility, mobility, etc and allocate him a nice workforce mobile cubicle. At 6 feet under. Trumps will continue winning - until we are back to a point where the working class has future to aspire to.