It's extremely simple. SerialBrain2 joins this community and writes illogical bullshit that sounds like real decodes. Lots of people are too dumb to figure out it is fake, so he gains a celebrity following of idiots. Then when the media needs to "prove" that Qanon followers are all deranged conspiracy nuts, they don't need to link to the actual Qanon posts because they can simply link to ANY SerialBrain2 post as absolute PROOF that Qanon people are crazy. Go read reddit/r/politics and search for any reference of SerialBrain2, shareblue mentions him about once every 30 seconds.