1. Everything rusts.
2. There is no permanent power source, unlike in sun synchronous orbit where you have 24/7 daylight.
3. The US has no ship building industry of any size.
4. Storms can destroy things.
There is no empty space on Earth unclaimed by governments. Given the results of the American midterms essentially all land is currently controlled by left wing governments, and the left is very anti-AI. Only China really wants to build AI at scale but they don't have enough chips yet. That might change, but even then not many companies want to upload all their IP to China.
So you can forget building more or less any large industrial projects on Earth for the foreseeable future. It may not matter. There appears to be a GPU glut starting anyway, so who knows if anyone will even need new datacenters for a while?