What benefits?
All along the way from construction (big bore) to system designs for cryogenics on never-before built large rings, superconducting materials and testing, build of specialty SC magnets, super large detectors for never-before ring energies, the computing systems that were being developed to anaylze the sensor data, SC cable winding machines, presses, cable testing machines, engineering for massive 10k and 15k amp dc power supplies, radiation detection and anlysis, and on and on. All designed first-time machines. And this is only for construction and setup.
When operating on daily basis, who knows. What is learned/benefits of FermiLab, CERN, etc. The main benefit is to find the Higgs boson, and then to begin put the pieces back together in desired ways for the desired purposes - drugs, materials, etc. This is/was the centrol goal in this big science. Spinoff tech is a big part of it as well. It is the unknown part, but invariably happens in such projects.