Any data center project currently under way or with plans to open within the next year or two has already place orders with NVidia or will do so very soon. Due to demand and lead times, you have to order to critical parts and systems today if you want to have half a chance of receiving them a year from now. Hardware supply lines are long and complex. I like to say that you cannot run a compiler and end-up with a warehouse full of chips.
The next fundamental reality has to do with competition.
Suppose company A foolishly decides to build a data center with only 10% of the chips they originally wanted based on the hype around DeepSeek. In the meantime, company B sticks to the plan and, perhaps, decide to take add the 90% of chips data center A did not take.
The net result will be the company A will be absolutely destroyed by company B. They will have nearly twice the compute capacity, which will translate to a huge competitive advantage across many fronts.
In other words, the selloff is, at best, ill informed. Market forces caused FUD. The smart one's took it as an absolutely massive buying opportunity. All you have to do now is wait.