It seems to me that there are a lot of misunderstandings here about how semiconductor manufacturing works.
Most semiconductor companies today are fabless -- they design and test their chips, but actual manufacturing occurs at TSMC or another fabrication house. The reason is that a semiconductor fabrication plant costs over $1 billion. To make this profitable, the fab needs to run 24/7. You can't compete if you build a fab and only take advantage of 25% of its capacity, because you have to amortize the factory cost. TSMC basically "timeshares" its fabs among many customers, in order to share its manufacturing capacity across many semiconductor design companies (such as Qualcomm, Broadcom, etc).
It costs millions of dollars to design and validate a semiconductor, before even hitting the fab house. Then, very expensive masks have to be made - mask costs can run into millions of dollars for some processes, and it's time-intensive, so you cannot have a mistake in your design. This isn't software, where you can recompile and re-test.
Once the masks are made, sample wafers are made and tested, and minor mask changes are made, if necessary. Here's the important part: Once the masks are validated for production, they are validated only for that plant. Occasionally, a mask can be validated for production at two TSMC plants, but never across two companies, like TSMC and UMC. It simply isn't done.
The problem is that when demand is high, TSMC puts its customers on allocation. Instead of 10 million parts a month, they'll cut you back to 8 or 9 million a month. This has obviously affected Apple and Qualcomm, so much so that they're offering up $1 billion for exclusive fab access. For some reason, TSMC said no. Perhaps the cost of the fab is greater than $1 billion, or they have limited fabs and their total revenue is higher if they simply run them 24/7 across a range of customers. I don't think Apple and Qualcomm are trying to corner the market, they're trying to ensure reliable part supply.
Personally, it may make sense for the US government or a private consortium to form for American semiconductor manufacturing, but it is no easy feat.
I hope this long post was helpful to some of you.