1. "Thread count" is for cotton, not silk. (Silk has a different thing to measure its quality but it's not generally used for sheets.)

2. "500 thread count" is not that high. 1200 is usually the "fancy" quality thread count. 300 is usually the lowest (though some types of cotton, like flannel or bamboo, don't use this at all).

3. As someone who uses a silk pillowcase for my hair, they are a freaking pain in the ass to wash? Who are y'all with whole-ass everyday bedding in silk? Also, silk stains like crazy. Every drop of sweat, cum, blood, and tears is leaving a puddle on those bad boys, and if you're lucky they will wash out.

4. However, what I think people are actually getting confused by is the fact a lot of fancy high-threadcount bedsheets are sateen. Sateen is a type of cotton weave and it does have smooth, one could almost say satiny, finish. But sateen sheets are definitely cotton.