Doomsayers, get what they want. Some historical predictors of the end of the world have bilked people out of money, had them join them in suicide, but not every doomsayer is ultimately evil. Some of those that preach or warn of the impending destruction of the world get an interesting little piece in history.
It’s hard to forget the person that is so confident in something that could change the world. Aside from the obvious panic that might ensue; being reminded that it could all end has a profound effect on many. Some may go on that trip that they always wanted to, some may go to their place of worship more often and others still might even be much kinder to people on that supposed day of ultimate destruction.
In one way or another, doomsayers get people to listen to them if they drum up enough support. Despite the often negative outcomes; we might just need that reminder every once in awhile to change for the better until the next time the world is coming to an end.