Not really my area of expertise, but this article lays out her perspective on this for anyone who isn’t aware: https://www.scientificamerican.com/article/the-world-doesnt-need-a-new-gigantic-particle-collider/
TL;DR - Many times the cost of the LHC and unlike the LHC, the gains are likely to be incremental instead of revolutionary. The same funding could do much more good elsewhere.
To your point, agreed that even small, incremental gains for science are more valuable than what we are likely to get from AI.
If the state of open source phones are anything to judge by, we will have open source cars at some point, except the foot brake isn’t working yet, so you’ll have to use the hand brake for now. Cars and phones both take a lot of resources to develop, and maybe you’ll be able to “de-Stellantis” your car at some point instead of going fully open source, but judging by the recent steps Google has taken to weaken de-Googling, I’m not sure how long that would last either.