"Mob mentality" refers to the behavior of a group of people who act as if they have a shared mind. It often leads to irrational or violent actions that individuals would not usually do on their own. Full definition
There's been quite of a bit of mob mentality driving the marketplace as the retail trader can feel empowered making public market calls on social media. (elementgroup.com)
We've seen online harassment, toxic comments and mob mentality in some cases. (gonintendo.com)
It would be nice if people in our country could be nice to one another, and not always take an angry mob mentality about everything. (religion.blogs.cnn.com)