The plot to attack the White House’s UFC Freedom 250 event Sunday involved at least 12 suspects across the US who adhered to an “accelerationist” ideology and hoped to bring down American capitalism, according to federal law enforcement sources. The FBI foiled their plans by infiltrating a Signal chat group planning the explosive attack — with a parent of one kid in the messaging platform reporting it to the police, sources told The Post. The suspects are in at least four states — California, Ohio, Missouri and Nebraska. They were plotting to gather in Fredericksburg, Virginia, to launch an explosive...