I have no problem with experts - sometimes you can learn a lot from them. Someone who thinks they know a lot about their given subject but actually don't (I include myself in this!( is NOT an expert.
A word has appeared over the last few years which applies to many of these YouTube "stars". Influencer. What a horrible word, but then I suppose you could define an "influencer" in the same way that you would define how a sheepdog works.