Outting Superman is big.
Outting the blur is soso.
(Lex was dead by the time the Blurr turned up?)
Outting an Alien is tacky.
Besides, information is power.
There's no benefit or glory in revealing Clark... YET.
Which is why most bad guys sit on the good guys secrets.
Batman teasing the Riddler that he was special only for as long that he and only he knew that Bruce Wayne was Batman, and that as soon as Nigma gave up that secret, he would just be another loser in a green suit.
Karen Page sold Daredevil's identity for a dime bag of heroin.
Price and cost is relative.