They have to plan their production in advance, with budgeting, contracts, and prices decided before the products are even manufactured. This is hard to do even when you're just trying to plan for the demands of legitimate buyers.

But every single day in the meantime, RAM prices will continue fluctuate, and arbitrage takes advantage of this. And arbitrate markets don't even necessarily track new RAM prices, if someone dumps a bunch of used LPDDR devices in China, people may harvest used memory for arbitrage.

For example, lets say they plan for how many people want to actually buy a 1GB Pi 5. Then they produce that amount. Then scalpers (hypothetically) realize they scape old RAM off discarded cable TV boxes for less than the OEM pays for new RAM. Then the legitimate 1GB Pis will be quickly scalped up off the market, and the market will be flooded with modified boards of higher capacities.