What do we do about this? Wrong idea. Each one of us does something about it individually. You think for yourself; you vet things yourself; you don't worry about the rest of the "crowd" and how they might be deceived. Evolution only has you socially rigged up to truly affect about 150 people, max, anyway.
But, if everyone carries out that solemn responsibility, things will be fine. Problem is, because of a lingering reliance on big media, most people don't. And it was a serious problem back in the days before crowdsourcing too, because the "gatekeepers" have told some whoppers over the last century or so. This was especially true around the time of Goebbels and WW II, and it has never recovered since, despite all the best intentions of journalistic integrity. The journalists did their best to hold the lie machines at bay, but that time has long since passed. A few decades ago, by my reckoning.
So, the horse has been out of the barn for at least that long, and we are talking about shutting the gate? Now? What the hell, folks? Mass media is a lie machine, and it functions because it is a lie machine, and all we've done is given the keys to the lie machine to everyone, instead of only the "gatekeepers." That, by my yardstick, is a profoundly good thing, although it will take a period of adjustment to become used to it.
Personal responsibility and a ready supply of grains of salt is all we have left. Don't believe everything you read. Since CGI advances, don't believe everything you see either. Welcome to the Brave New World. IMHO, it's a "good thing," but you have to be careful what you choose to believe these days.