DRAM prices have quadrupled, while HBM is mostly locked in long-term contracts, with price increases capped at around double. Even if the original profit margin was 80%, it still can't compare to the profits after DRAM price hikes. One is free to raise prices, the other is restricted by long-term contracts. It's not that HBM's profit margin isn't high enough, but DRAM makes money faster and more enjoyably after the price hikes.