They can be. Think of the incidents like that lady calling little kids racial slurs (then getting a fat check from fund raising), or how some people act in customer service situations. Or I mean, random assaults and shootings. Online can give anyone anonymity, which is definitely often abused, but some people feel that way in public surrounded by people they don’t know.

I’d add that there are some people who, when interacting with them online, we really didn’t get along. But it was very different meeting them in person. I’ve had the opposite be true as well, where I thought I would really like someone I was getting to know from an online community, and then really didn’t hit it off with them in person. So, that’s not as far as being horrible or toxic, but just that I have experienced people seeming really different in either circumstance. You can also find many anecdotes about people knowing someone who seemed really chill in person, and then on social media they’re really awful.