Well you still get the establishment of 1) large industrial buildings 2) water/electricity distribution 3) trained employees who know how to manage a data center
Even if all of the GPUs inside burn out and you want to put something else entirely inside of the building, that's all still ready to go.
Although there is the possibility they all become dilapidated buildings, like abandoned factories
The building and electrical infrastructure are far cheaper than the hardware. So much so that the electricity is a small cost of the data center build out, but a major cost for the grid.
Of the most valuable part is quickly depreciating and goes unused within the first few years, it won't have a chance for long term value like fiber. If data centers become, I don't know, battery grid storage, it will be very very expensive grid storage.
Which is to say that while there was an early salivation for fiber that was eventually useful, overallocation of capital to GPUs goes to pure waste.