The cheapness of the building is not the problem that is being dealt with.

The construction of the building w/ zoning and the political fights and utilities arguments and years of time and whatever is what is being dealt with by putting it in orbit.

I bet you could build a fully off-grid DC that didn't guzzle water for less money than launching a rocket today, and there would be thousands of people lining up down the block to sell you more than enough land to do it a thousand times for cheap. This just isn't happening yet because it is still quite possible to build on-grid DCs supplied with fresh water for cooling despite what some people would have you believe.

And then when you build on the ground you could even send people to it to swap hard drives and GPUs when they inevitably fail or upgrade them to keep them current. At lower rates of failure than they would in space because we have a planetary magnetosphere protecting us from cosmic rays.

It would be extremely funny if putting things in space is cheaper and faster than dealing with zoning and local politics.

It implies that China, which can cut through much red tape and has great (and improving) utilities and infrastructure, lots of energy, can just build normal datacenters and save the cost of dozens of space flights.

Building in space adds engineering complexity. Heat output requires radiators. Radiation damages equipment without shielding. Repairs require a spacewalk. All this for what, better solar panels? If you think local zoning challenges are an obstacle, then you have 194 other countries to build in. Going to space is probably the worst option. Even putting a data center on a boat is probably a better choice and that still sounds like a stupid idea.