I've posted previously about why I believe that misinformation is the single biggest threat to Democracy.
To help me explain why this is so, I offer, for example, the following video in which Trump rally attendees are interviewed and are asked what they think about the 1/6 investigation:
Interviewees exhibit a complete disconnect from reality. Numerous interviewees don't even know the significance of 1/6. Others spout conspiracy theories as to what transpired - for example, that 1/6 was orchestrated by Nancy Pelosi in an attempt to discredited Republicans.
Several of the interviewees agreed to view footage of the proceedings. A clip was shown in which Barr (the Attorney General under Trump at the time of 1/6) stated that the claims of election fraud were bullshit; another clip showed Ivanka Trump saying that she believed Barr.
One of those who agreed to view the clips, shook his head and obviously went into a deep think. At the end of his thought process he decided that something was very wrong. He concluded that the clips shown to him were fake or that the footage was taken out of context.
A second individual concluded that the Ivanka clip was a fabrication. He thought that an Ivanka clone was filmed; obviously, he reasoned, the real Ivanka would never say such things.
Yet another individual who viewed the clips seemed to correctly process the information presented to him. But when asked whether or not he was going to attend the pro-Trump rally, he said absolutely that he was going to. Apparently he simply brushed the footage off as irrelevant.
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Watching the above video helped me understand why disinformation needs to be regulated.
Witness attendees of Trump's rallies. These people aren't rational. They actually believe the lies they have been told - to the extent that they're largely beyond persuasion. The repeated lies and echo-chamber reinforcement have turned them into a secular cult. It would take an intervention followed by intense deprogramming to possibly return such people to rationality.
Irrational beliefs lead to irrational behavior. And irrational behavior may lead to extremely poor decisions that put the very lives of the mislead in great danger; or, worse still, that pose a threat to society at large.
Roughly 1/2 the USA is under the sway of irrationality. These such, acting collectively, are well-capable of voting into office frauds and demagogues who would do society great harm simply to advance self gain. And that is why disinformation needs to be regulated by the government.