"Someone who sounds impressive on social media (FB etc) and has strong opinions, must be right -- even though I don't know them at all, or know anyone who knows

"Someone who sounds impressive on social media (FB etc) and has strong opinions, must be right -- even though I don't know them at all, or know anyone who knows them, so I have no basis for knowing if they are really honest or reliable. But they must be right, because they said it a lot and seem popular to others."