If you look at the history of pure Physics research I think its contribution to society is exceptionally high. Purely from a particle physics perspective in recent times you can point to cancer diagnosis and treatment (PET, CT, MRI, creation of isotopes using accelerators in hospitals, direct cancer treatment using particle beams etc.) and everyone's go to example of the World Wide Web, which has completely revolutionised how everyone communicates and accesses information. The internet has a huge impact on every single problem the world has to solve and so you can almost end the argument there. Yes it would have come in to existence in some form without CERN, but not in the open source format we have it today. As for E=mc^2 and special relativity
Incubus , nuclear power plants are currently the only realistic long term source of power that can meet global demands, and GPS navigation depends on special relativity and has countless applications worldwide. We might not even be aware of all the serious issues there are to solve in the world if it wasn't for people in human history "wasting" time and money playing with things like electricity and aeroplanes.
The annual CERN budget is not even ridiculously high - roughly $1 billion per year split between 24 countries - and let's not forget the significance of having an organisation where 24 countries can successfully collaborate, by the way! Many other organisations have much larger budgets - NASA is $18 billion per year, the UN $13 billion per year - and the worldwide spend on defence is $1630 billion!