Ok, I'm going to annoy any of my former colleagues who read this by saying this, but modern particle physics is about the least likely field of science to ever produce economically useful results. It's hard to argue otherwise. However, and this is a big however, even though the science itself (the search for the Higgs and super-symmetry and so on) is arguably worthless, the research into sensor and computer technology that is what the people at CERN (as opposed to theoreticians looking at the results) spend doing is undeniably incredibly useful. As mentioned, the internet is a prime example.

There are two points here. One is that there are dis-economies of scale if you focus a nations efforts too exclusively on one scientific field. I don't really feel like going into detail as to why that is, but mainly it's that most good ideas come from cross-pollinations between disciplines, which is hard to do without a lot of disciplines.

The other point is that high-energy physics (as opposed to condensed matter physics or especially biology) has a much harder time getting funding from the private sector, because any useful results it produces are less likely to be easy to directly monetize. That is, better understanding of physics helps everyone live better, but mainly by allowing other people to design better technology. It's the other people who make the money, though. Unlike biology where whoever figures out what protein cures twitter addiction can directly market this discovery to drug companies. Physics funding is the standard public goods problem.