I am guessing there is some fluidity between these markets. If consumers get priced out of the DDR5 market, the consumer DDR4 price increases as well. It is the same with cars, if the price goes up for new cars, it usually increases for used car market as well. Same with energy, price goes up for oil, all things beeing equal, other energy carries will increase to some degree.

Not sure if that's what you've meant...

Because the prices of ddr5 are causing people to use substitutes

The lines that would have made consumer-level stuff are being reduced in favor of the higher profit margin/demand products. That means more supply of those other products (but still not enough) and lower supply of the consumer-level stuff (driving up prices).

If memory makers can fill their order books with only a single type of memory (whatever that is), then that would be preferable to them, I suppose.