From what I've read (and the interviews below), most cells, other than erythrocytes (RBCs) produce their own cholesterol; one of the functions of HDL is to ferry any excess to the liver.

Best intro to lipidology I've ever run into is a 5 part series Peter Attia did with Tom Dayspring. Very much worth a listen if you're interested in the mechanics of LDL.

HDL is much less well understood. He's more recently had an interview with Dan Rader on HDL.

As a side note, I'd point out that statins are very much overprescribed. For most people they hurt more than they help, most notably in their blocking of K2 leading to plaque calcification, but there are also links to congestive heart failure. See: Statins stimulate atherosclerosis and heart failure: pharmacological mechanisms for more on that. Also, if you’ve just turned 65 and your doctor is now suggesting statins, they use an online calculator to see whether statins are recommended, and it looks as though a primary variable in the formula is “over 65”. Ask him/her to run the calculator with a lower age.