> if I'm being asked to believe that they swung the election to Donald Trump with $100k in Facebook ads and a group about dogs

I'm not sure anyone's asking that. The social media results were not about ads bought. The issue was about accounts pumping specific content which was then reshared by actual voters. (and official news outlets) Those accounts were happily switching between being really interested in US, then French elections, then Brexit, with some middle east commentary in between. There's lots of research about them a few google queries away.