Everyone underestimates how HEAVY the collider is, how often sensor modules need to be changed and mainly that the ring is just one part of the entire group of big buildings you need for this.

You need to create different beams of different makeup from different sources, different loops to make the beam hit sonething and maybe return the products into the loop, you need extensive sensory equipment where the collision happens and different sensors for different experiments.

It is just SOOOO much cheaper, easier and better to build it underground instead of in space.