> people may draw completely different conclusions from the same facts
Le Bon points out a more basic issue. He wrote about the kinds of crowds who used to storm the Bastille and so on—and appear to have returned to American history today after a long vacation. He concluded that the members of such crowds simply don't do things like considering facts or drawing conclusions. Instead, they associate chains of images and follow suggestions from prestigious leaders. TV advertisments do exactly what he suggested, and so does Donald Trump. It appears to work.
This puts me in a dilemma. As a physicist with egalitarian tendencies, I want everyone to take action that will provide the things they want and need, according to valid arguments founded on the laws of nature. But apparently, one of those laws of nature says that valid reasons have nothing in common with the reasons people do things.
Bernays resolved that dilemma by telling people like me to manipulate everyone else into doing what (we believe) is in their best interest. I'm really uncomfortable with that position, but it's hard to see an alternative.