First off, no one said they had to be effective to be insurrectionists. Trying to rob a bank is still a crime, even if you get no money. An unsuccessful coup is still a coup attempt, even if the colonels leading it get their heads lopped off.
Second, creating a Constitutional crisis is a MUCH better idea than starting a shooting war against the government.
Biden is wrong about one thing; the idea isn't so much to take over the government by shooting war if it turns tyrannical. The idea is to make such a prospect appear painful enough that it isn't worth taking a tyrannical turn.