Because of the engineering effort required to build such systems, that no one has built before, means there is a gigantic amount of R&D discoveries that can be eventually applied in other fields outside particle physics.

Mechanical, electronic, informatics, chemistry, physics,...

Hence why CERN eventually created an industry collaboration office, responsible for finding business partners that would like to make a business out of such discoveries.

https://knowledgetransfer.web.cern.ch/activities-services/co...