Excerpt from this article:
Two of modern society’s most disruptive forces — anger among many men over social changes they see as a threat, and the rise of social media upending how ideas spread and communities form — are colliding. The result is that movements like the incels are becoming at once more accessible and more extreme.
Although attacks like the one in Toronto that killed 10 people are rare, the hate being spread online is leading increasingly to threats and calls for violence. More often than not, the threats target women.