Never. I have some coins that I got for $500 in 2014 and I'm never going to sell, especially not in a situation when it goes to a million dollars. I'd rather use it as a collateral, use it to show my credibility, for proof of ownership. I'd be able to borrow fiat money and invest it knowing that if anything goes wrong I'll be able to cover losses with my BTC. Having a few million USD as backup can work wonders when you know what you're doing.
Are you sure you are really making an investment or has bitcoin become an obsession for you? bitcoin is equal to money so it should be used just like fiat, doing it hodl until you die is not a sensible thing to do, what would be the purpose of that? your family will need money and you will be being mean and selfish to hide bitcoin because you are obsessed that you can't sell, honestly this thought is not a good thing and no investor or person who has good being, has feelings or knows what bitcoin really is
Well, the funny thing is that since everything related to BTC began, most of the people who owned it did not have it for its monetary value, they had it because they liked technology and because they are something like enthusiasts, which is something that is respect. If a person does not want to sell his BTC and prefers to borrow FIAT money, it is something that is not very common, maybe he does not have needs or is very comfortable with what he earns and is stable, if this is the case, it is understandable, but in difficult situations or if you have an emergency, I am sure that you will use it, because it is normal, after all, Bitcoin represents money.