String Theory requires super symmetry. Super symmetry requires super symmetric particles called "sparticles". If sparticles are real, the LHC should have found at least one of them. It did not and thus super symmetry doesn't exist. If super symmetry doesn't exist, then String Theory is wrong. Simple as.

The fact that some physicists spent their life working on a theory that's false doesn't mean that theory hasn't been rather thoroughly disproven.