There are numerous flash manufacturers all racing each other to build out capacity and increase density because they want to eat the HDD market.
DRAM is controlled by a small cabal, all of whom have multiple convictions for price fixing and collusion. I believe Hynix shipped some sacrificial C-suite execs to do prison time in the US over it. To a large degree no one is building out DRAM fab capacity as well.
DRAM prices have stayed high because the manufacturers want it to stay high and are colluding (either explicitly or implicitly) to keep prices up. The capital cost to compete is enormous: many billions before you can make your first sale. The day you break ground memory prices will mysteriously drop so low as to make your venture unprofitable, meaning your commercial loans get called in and you go bankrupt. Everyone understands this and avoids attempting to compete.