I’ve heard that but not sure I believe it but at the same time like I said I don’t think cholesterol is bad.
Your body makes cholesterol. Dietary cholesterol has no effect on cholesterol levels. In any event it is unproven if high cholesterol levels are the cause of heart disease.
This has been proven for many years but some doctors still recommend a low cholesterol diet because they are uninformed.
It's generally accepted that arteriosclerosis (hardening of the arteries) is caused by inflammation of the arterial walls. This is promoted by eating a diet high in simple carbs and sugars.
Your father's body is making all that cholesterol that is the cause of his very high levels. That's unfortunate but it has nothing to do with his diet.
Do you also have this condition of abnormally high cholesterol and triglyceride levels?
Triglyceride levels can rise as a result of eating a diet containing hydrogenated fats which are found in processed foods like margarine, peanut butter, baked goods, coffee creamers, non-dairy whipped toppings, etc. Your father's levels are out of sight and while eating hydrogenated fats can raise triglycerides, they could not alone be the cause.
In this case it is genetic so it's important to find out if you also have this problem.
In any event, manage your bodyfat % to a reasonable level, avoid hydrogenated foods, simple carb and sugary foods, eat fiber and exercise, including some form of cardio several times a week.