The problem is even after they die they don't go away. And then things just get worse. We find for example,-- that Natan from Gaza became much more influential after the Shatz [Shabatai Tzvi] was exposed. I can't prove this if you have not read his basic books, but for those who are aware of Natan from Gaza's doctrines they can find them in all books of the religious world today that deal with "Hashkafa" world view issues. If you did not know better, by putting them side by side with books that are learned widely in the religious world you would say that they simply copied over his ideas--sometimes word for word. Go out and check this yourself. It is easy to verify. [If you have the stomach for this kind of research.]
It is better if you trust me on this. I am not happy I had to learn all of the above the hard way. And once and person goes into this stuff it is like wrestling in the mud. One gets dirty. I know this fellow Michael who also did a lot of this research. He went to HU and xeroxed all the writings of Natan of Gaza and learned them and he saw everything that I am saying here. But it stuck to him, He even tried to brig the soul of Natan from Gaza into the world and hurt himself and his family by dealing with these terrible kinds of energies. And he is the only person I know that even had a chance at succeeding making any correction. If he failed, I don't think anyone should get involved in this terrible stuff. Just know to stay away from all the false messiahs;out there. And take the Gra's advice. Don't go near them. They do not often announce this. They leave it to their followers.
I am thinking that it would make sense to make a point to be against false messiahs. I tend to want to see the good in every person --even bad people. But with false messiahs it makes sense to judge them unfavorably. The reason is they are in the category of מסית ומדיח people that try to entice others to do idolatry. In that case the Torah says not to judge them favorably.
If people would listen to me I would say that just like in Germany there are strict laws against certain cults as is well known, so should the case with false messiahs. How hard could it be to pass a few laws to protect innocent Jews from the clutches of these charlatans? Or at least have sane Roshei Yeshiva speak out against them like Rav Shach used to do?
Not all markets sort out the truth. The marketplace of ideas certainly does not. No matter what religion you are at least half the world is against your beliefs. The fact that lots of people believe a false doctrine means nothing as for its truth value. Rather for its entertainment value and emotional value. But that is not the same as truth,