I'd say the 2016 election proved how hard we are to manipulate. Hillary lost despite spending more and having nearly the entire media (with only a few exceptions like Fox) on her side.
>A December report from Harvard University’s Shorenstein Center on Media, Politics and Public Policy delivered some sobering news for all those investigative reporters who may have supposed that their Trump exclusives were changing the world: None of them were breaking from the pack. “Clinton’s controversies got more attention than Trump’s (19 percent versus 15 percent) and were more focused,” noted study author Thomas E. Patterson. “Trump wallowed in a cascade of separate controversies. Clinton’s badgering had a laser-like focus. She was alleged to be scandal-prone. Clinton’s alleged scandals accounted for 16 percent of her coverage—four times the amount of press attention paid to Trump’s treatment of women and sixteen times the amount of news coverage given to Clinton’s most heavily covered policy position.”
It's hard to say that the media was on her side when they gave billions worth of free coverage to Trump. They also gave her email scandals equal weighting compared to Trump admitting to sexual assault and directly asking a foreign government to hack his opponent on live television.
As Bernard Cohen reportedly said, the press may not be successful much of the time in telling people what to think, but it is stunningly successful in telling its readers what to think about.
Seems to be true in this case. They covered Trump, which made him the person people think about.
They told people to hate Trump. The electorate didn't listen.
Back to the original question, does that mean we're easily manipulated?
How can you agree that "the press may not be successful much of the time in telling people what to think" and at the same time think we're easily manipulated?