Earth has massive amounts of mostly unused land that is comparatively close enough by speed of light in fibre.

vs Space:

* Can drive a truck out there

* No limit on weight or dimensions (within reason)

* No giant explodey thing transporting it to into where it needs to be

* No constant falling towards the earth that needs to be averted with thrusters

* If building in the middle of nowhere there is also lots of space for solar panels

* Heat can be rejected into the atmosphere/earth/nearby bodies of water etc instead of radiation into the vacuum of space

* De-comissioning it doesn't also involve slamming a DC worth of mass into the atmosphere and burning up otherwise recyclable materials.

* You don't look like a doofus for doing bad math.