These investments used to be planned years in advance. They aren't anymore.
"Asks" are coming in from all sorts of AI players, and the most limiting factor is the availability of the electrical infrastructure in any particular region.
Building datacenters is now reliant on four things - electrical capacity available from the utility, labor, inventory of mechanical/electrical distribution, and land bank/permitting.
Data centers were definitely built with additional capacity "to just sit there" as long as there was a long-term lease for a cornerstone customer. This is why in the past it was a "buyers" market with competition driving pricing down, since multiple providers had available capacity.
What we're seeing now is the large AI operators buying entire buildings and campuses of inventory, on sites that are nothing more than dirt. No building, no utility, no approved permits. Just a plan to have everything available in 1-3 years.