Most Americans own some means of accessing the news (be it television, electronic devices, social media). Even if you don’t regularly sit down to watch the latest MSM talking shithead, just one impression of events (as well as second hand impression via word of mouth) can be enough. Bear in mind that social ostracism is also always an implicit concern for breaking with the perceived “consensus”.
This is why those rallies happening now are so important (regardless of what I think of IfNotNow) and why MSM is tripping over themselves only selectively reporting it.