My saintly Dad told me decades ago (when they were telling us to not eat eggs): we are animals, our bodies make cholesterol!

He also said that eggs also contain lecithin to process the cholesterol: "Lecithin in eggs is primarily found in the yolk and is a type of fat that helps with fat transport in the body. It is also a source of choline, which is important for brain health and various bodily functions." wiki

We only had margarine when we couldn't "afford" butter. Then they decided, Butter is Better and worth the extra cost.