To be fair, the base was already there and logistically essential. The IceCube topside building is just a part of the Amundsen-Scott South Pole Station, about a km or so from the Elevated Station.
This image* from Wikipedia surprised me. The topside building is...you could say...the tip of the iceberg. The detectors span a huge area going over 2km deep. The predecessor AMANDA array was also down there.
The building is just for housing the data gathering and comms equipment and whatever maintenance and engineering stuff the array needs. I don’t think anybody physically works there regularly.
