I think it's fair to compare the LHC with past scientific experiments but if you do you should remember that no past scientific experiment destroyed the world and therefore you don't get a prior probability greater than 0 by that process.

The LHC even didn't worked the first time around. You could say the predictions of how the LHC was supposed to work were wrong. There however millions of different ways that the LHC can turn out results that aren't what anybody expects that don't include the LHC blowing up the planet.