Hi EZ4HZ,
There is more about sheets and fabrics in post #7 here and the posts it links to but thread counts that high with cotton are very misleading and probably aren’t a meaningful indication of the quality of the fabric. Even if the thread count was accurate … it probably wouldn’t be the best choice for cotton sheets because they they would be much less breathable than lower thread count sheets that used higher quality fibers.
There’s are some good articles about thread count here and here.
Thread count when you are looking at sheets is the equivalent of coil counting when you are looking at mattress innersprings. Both are only one of many variables that can make a difference in the quality and “feel” of the product and both can be more misleading than helpful.
Phoenix