Why can't Riot buy more virtual storage?

Riot brings in a whole lotta revenue, no doubt, and have the manpower to support that too. If they can afford to have 1000 employees (or something like that) why can't they afford to buy, idk, hundreds of terabytes of space (or whatever they need) to support replays? Is it too costly? Is it not possible due to the way the game was originally coded? Is it too hard to implement?