That's in part because of all the anti-China propaganda on big media and youtube. In youtube, anti-China content, specially content from big media (BBC, sky news and the likes) and CIA-backed content, is recommended to much more users than pro-China content. Just look at the number of views of anti-China videos vs neutral or pro-China channels. Anti-China videos easily get millons of views, while the best of the best pro-China videos only reach tens or hundreads of thousands of views (one or another may reach millions by using a super catch thumbnail and title). The pro-China videos are mostly recommended to people that already watches pro-China videos, while anti-China videos get recommended for everyone on youtube. The result is that a huge amount of youtube users believe anti-China crap.