It is all about companies trying to achieve supremacy to avoid being the losers. Since computing power is required to achieve it, they try to maximize the hardware pipeline build up again to remain as the top dog. They are not paying for it themselves in any case. They are subsidized. The public markets get the bags and pays for it. It is a subsidy program like overproduced milk. Milk become canned milk, cheese, protein powder... to be stored.
In order to prevent infrastructure from sitting idle and bleeding cash, they save the surplus in pre-training. The glut is disposed via compute credit often used by startups.