Left Behind novelist Tim LaHaye has been profiting off of the imminent apocalypse for over a decade. But he doesn't think much of en-vogue doomsday prophet Harold Camping: his May 21st rapture prediction is "not only wrong but dangerous," LaHaye warned in a post on his website, before calling Camping's rhetoric "bizarre" and "100% wrong!"
Fair enough: that's what everyone other than Harold's true-believers has been saying. LaHaye also quotes the "no one knows" the "day or hour" verses as evidence that the Family Radio pastor is misreading the Bible. His point underscores just how dubious Camping's math and multiple doom predictions are. It's just interesting to hear it from an author who's sold 63,000,000+ novels that are based on a "literal interpretation of Bible prophecy" and have titles like Armageddon, Soul Harvest, and The Rapture.
The difference in apocalyptic theory, as LaHaye points out in his post, is that his stance can be clarified as "PERHAPS TODAY" (caps lock his), rather than giving a specific date for judgment like Camping does. But part of the reason why the Left Behind series was so successful (and spawned movies, video games and a kids series) is because it actively fantasized what would happen if the Rapture happened right now.