I am observing increasing number of people is now seriously believe in "Moon Hoax". Definitely more than back in 70-80th. Why is that? Generation of YouTube? Deliberate propaganda?
I don't think anything about that is "deliberate propaganda".
It's just nutjobs gathering and gatherings of nutjobs creating more nutjobs. It's much easier these days with "social" media.
Even Alex Jones, a figure so obviously deranged with claims that sound like satire, has been selling supplements and merch. All because these days anybody has a platform and monetizing lies is easier than ever. People will believe anything, especially if it's 'published in a scientific magazine', nevermind that the publication has no credibility, reliable sources, or academic integrity. This is how anti-vaxxers got their start, after all.
This is obviously less ideal than someone actually understanding an idea they profess to hold, but it's far better to have support around beneficial ideas. It's not hard to imagine a lot of important issues fitting into this: support for liberalism and demoracy, support for global warming, support for coherent ideas about vaccines, etc. These all require broad public support, and the truth of the matter is that many people generally don't spend much time evaluating why they believe what they do.
I understand this is not a perfect point of view: eg, who gets to decide what the "best" ideas are.
It's an illness that demands rejection of overwhelming proof, it leads down dark paths, much like how arsonists become murderers these things need to be cutoff at the stem. There's nothing wrong with that