We are not trying to convince ourselves about the utility of the LHC. The LHC is useful and that's it :)

More seriously, the LHC is a discovery machine in the sense that it will explore an energy regime never probed before (in parallel of getting a lot of data in the Standard Model domain, allowing for precision measurements and probes for deviations). And an exploration does not guarantee any discovery at all. We are just exploring. Who knows what will be around the corner (nothing is a possible answer)?

In addition, the LHC is not the ultimate discovery machine. This is just wrong. The high-energy physics community is currently discussing the next generation of electron-positron and hadron colliders that could be built. In any case, I am pretty convinced that any investment will yield positive benefits for the society. And I hope that both a new electron-positron and hadron collider will be built during my lifetime.

But I fully agree with you about the problem on funding. We need to convince politicians whose lifetime as decision-takers is of about a few years that huge physics experiments are useful... And the absence of LHC discoveries does not help.

Coming back to my post, I was trying to show that taking the LHC as an investment, the society will always get some return of it, no matter we have any discovery or not.