Do they want to get into a commodity business like RAM production? Maybe not, but if prices stay high long enough that demand for their products falls off, they might think about it.
I know that I personally and my employer are cutting way back on new technology purchases and squeezing as much as we can out of old equipment due to the cost of RAM and storage now.
Fabs are a cutthroat business that's very hard to get into. It costs billions of continual investment to stay a float. That's why there's really only about 3 different companies with cutting edge fabs. TSMC, Micron, and Samsung. Even intel, who built a huge portion of their business on cutting edge fab tech, has struggled to keep funding it. AMD got out of the fab business almost a decade ago (spinning off global foundries) and that spin off is no longer cutting edge. AMD uses TSMC.
Fabs are some of the most expensive factories to operate on this planet due to a constant need for brand new equipment and cutting edge research. That's why there's not an Apple, Google, Meta, or Nvidia fab. That's why there's not an AMD fab. That's why Intel fabs are treading water.
Without the constant investment, you very quickly find yourself in the company of yet another cutthroat industry, the "not cutting edge" fabrication industry. And that, by and large, has already been locked up by about a dozen fab companies.
There are some ways to get this off the ground much quicker. One or more companies could buy an existing non-leading-edge fab like GlobalFoundaries. That buys a lot of expertise so you're not starting from zero.
DRAM also benefits from being very regular and relatively simple. It used to be what you bring up on a new process node to help prove things out.
It also isn't impossible to reduce reliance on ASML if you're willing to throw money at it. That's definitely a super-long-game move but it could be done.
I'm not going to argue that someone is going to do any of this but if demand is sustained it is possible.
Meanwhile, I believe SOTA is at least 3 or 4 node shrinks beyond that 7nm process. It'll take years for them to catch up to where micron is currently.
So much for efficient free markets.
In addition, the know-how is concentrated in Taiwan. You literally can't train enough people in enough time to move everything out of there.
Where are SK Hynix and Samsung located again? Or 95% of Micron's facilities?
For example, Micron is actively building a few new fabs. One of which has been in progress since Biden (pretty close to my home in fact). It's not going to be completed for another 5 years at a minimum. And this is a company that has the experience and partnerships for producing fabs.
Yes, a new company might decide they want to enter the market, but even if they decided, today, "Yes we'll do this" I'd expect a minimum of a decade before they start spinning out their first chips. That's also at least a $1T investment at this point to get started.
Not even they necessarily have the experience to do it! Intel has a policy called "Copy EXACTLY!" for fab construction where they make every irrelevant detail the same as their last fab, because they don't actually know which of the details matter.
After spending a lot of time studying the problem what they finally realized is they built the building too close to the interstate and vibrations from the interstate were ultimately making their way into the factory causing errors.
To combat this problem, they spent millions retrofitting shock absorbers onto the building.
It's not shocking that intel would do the same because even the slightest movements and vibrations can spoil the chips. Putting a restroom in the wrong spot might spoil a batch when someone flushes the toilet.
Again, people might want part of it, but they are also a bit smarter than you are and read history books to see exactly how this is going to play out and then they gladly walk away before they light their money on fire.
They sit on billions because they avoid spending their money as much as possible.
The amount they spend on RAM in surrounding few years would represent almost nothing to the massive money hole that would happen if they tried to make their own fab.
Also, these problems tend to affect the entire market, which means if you're big, you're fine. It's when problems don't affect your competitors but affect you that the real issues for these companies crop up.