I might add: 4. They're looking to make a profit. Either by selling ads, products, or by building an audience to exploit later. Saying outrageous things you do

I might add: 4. They're looking to make a profit. Either by selling ads, products, or by building an audience to exploit later. Saying outrageous things you don't believe can unfortunately be quite lucrative. Perhaps it falls under your second category, but I think the profit motive makes them even more motivated & nihilistic than a mere troll.