Bunch of degenerates are terminally online on an almost anything goes website.

Stormfront and others see the site as ripe for manipulation and recruiting.

Over a decade, 4chan is dragged rightward by concerted effort from various fascist groups.

Manipulation of social media increases into the 2010s, fueled now by governments attacking mostly the USA and Europe.

QAnon gains popularity after others on 4chan fail; CIAnon, FBIAnon, etc etc. Right wing, hateful, insane, or just plain dumb normies all slurp up the conspira-juice.

russian asset becomes president. Incompetently tries to destroy government and nation while stealing as much as possible.

russian asset loses election. Decides to try to destroy the USA a bit more by declaring the election fraudulent without a shred of evidence. Tries hard to get result flipped to republicans for... reasons.

Dumb ex president thinks he can just demand Congress elect him. Holds a rally the same day as the election is certified, tells attendees to "fight for America's future, let's march to the Capitol, I'll be right behind you!"

After they organized partially on 4chan, Enthusiastic chodelet troglodytes storm the Capitol.