> Low cholesterol production is an extremely serious condition.

This is correct, but not in the way you mean it. We know people can effectively produce no LDL cholesterol in their liver and have positive health impacts - these MR studies are a big part of what drove this entire class of cholesterol medications. And the monoclonal antibody versions of PCSK9 inhibitors have shown basically the same results.

Virtually all human cells can produce cholesterol locally de novo, including your brain.