Somebody once explained that when a theory is shown to be wrong, its proponents will keep on believing in it. It is only when they pass away that the younger generation can move on.
None of this applies to string theory. To be shown to be wrong there must be something to present. The mathematical construct that is currently associated with string theory is not in any form that can be subjected to any scientific testing.
What was shown to be wrong is supersymmetry, which is a prerequisite for the currently favored version of string theory – super string theory. (The non-supersymmetric version of string theory fell into disfavor decades ago.) The Large Hadron Collider did not see the expected particles predicted by supersymmetry. Well, to be honest, there is a small change that it will see something in the third run which has just started, but I get the feeling that people are not exactly holding their breath. I’m willing to say supersymmetry is dead and therefore so is super string theory.
Another reason why things are different with string theory is because the proponents found a way to extend the postmortem activity in string theory beyond their own careers. They get a younger generation of physicists addicted to it, so that this new generation of string theorist would go on working in it and popularizing it. What a horrible thing to do!
Why would the current string theorists mislead a younger generation of physicists to work on a failed idea? Legacy! Most of these current string theorists have spent their entire careers working on this topic. Some of them got very famous for it. Now they want to ensure that they are remembered for something that worked and not for something that failed. So it all comes down to vanity, which I’ve written about before.
String theory was already around when I was still a student several decades ago. I could have decided to pursue it as a field of study at that point. What would I have had to show for it now? Nothing! No accomplishments! A wasted career!
There was a time when you couldn’t get a position in a physics department unless you were a string theorist. As a result, there is a vast population of string theorists sitting in faculty positions. It is no wonder that they still maintain such a strong influence in physics even though the theory they work on is dead.