Sandisk doesn't make DRAM.

Micron's stock price did go way up, after they stopped selling DRAM to the consumer market. It has been flat for several months though.

For comparison, SK Hynix stock is flat YoY and Samsung's stock did go up this year, but has come back down a bit (they're also much more diversified). Those are the only other companies outside of China that actually make DRAM at scale. There's also CXMT, which is making inroads, but its stock is not traded on any open markets, and the company is heavily backed by the Chinese government.