Investors chasing the ideal of not having to employ any people while still making money somehow. And, of course, being the company to provide all the AI; in a gold rush, don't dig for gold, start selling buckets.
There's only so many companies involved as far as I can tell,but these datacenter stories seem everywhere?
The big providers lease capacity in addition to their own capital investments. It helps them hedge risk. When the merry go round stops on AI, these will all go bankrupt, and H100s will be like a circa 2001 Aeron chair.