Some of them are stupid and mean, but some are just stupid and think they've found a secret code or way to 'hack the legal system'. I agree they're time-wasters and the people who sell them on the scam are legal fraudsters, but I also think it highlights a problem of excess complexity in our legal system to the point of seeming arbitrary and impenetrable. The sad thing about most sovereign citizens is that they're not usually trying to accumulate big fortunes or run elaborate criminal schemes, they're trying to get off the hook for petty criminal or administrative violations that have disproportionately impacted their lives.

I kind of agree with Plato that a society with too many laws ends up becoming tyrannical because it's impossible for the average person to keep up with them all. Also, in our modern society every wrong thing you do follows you around forever, and our bureaucracies tend to be Kafkaesque (also due to stupidity rather than malice). While I do not agree with the trope that 'most people commit three felonies a day', simplicity and clarity would be a good foundation for better civics education.