Particle acceleration as a technology has some applications/ From the top of my head: Synchrotron radiation is used for material testing, in semiconductor fabrication its is used to implant ions, there are applications to cancer treatment. The technology that gets developed to actually carry out the experiment helps to train generations of high tech workers (think radiation hardened semiconductor circuits for example, specifically in the detectors) and develop advanced fabrication methods (needed to build the superconducting magnets for example). From a policy perspective, the fact that it also advances the borders of human understanding is just a nice side effect.
