Technically, they are buying manufacturing capacity. Datacenters don't use consumer DDR5 sticks with epic RGB lighting, they use server grade hardware, and are contracting the manufacturers to make stuff for them at high premiums. That means they either aren't making consumer hardware at all - causing shortages - or if they are, they are asking a premium because they could be using the time better making the server stuff.

Kind of like a medieval baker - if the king offers to buy 1000 cakes from you at a ridiculous price, you aren't going to be spending time baking any bread for the peasants to eat.