They aren't keeping supply low.
They have two massive DRAM fabs (56000 m^2 cleanroom size each) that they started construction on in 2022 and 2023 in Idaho, with production starting in 2027 and 2028.
Which are exactly the two years they are threatening tighter supply.
The point they were stating was that if they kept up the high prices, that leaves room for a low priced competitor, likely from China, to occupy the lower end (and larger) share of the market. Like what BYD did to the EV market everywhere except the US. Or what Chinese mobiles did to the smartphone market. Eventually they become so powerful that they start going upmarket, trying to catch everyone in the higher end segments too. And by the time the Western companies think they can retaliate, too bad, China's got them by the bollocks on raw material.