I don't think that a real whale keeps all his coins on hardware wallets. Cold storage, maybe with multisig would be the proper way. Also splitting, especially to not attract attention for the amount held in one address, may be in order. HW is great for smaller amounts, like what they'd keep with them when going out.
However, I would also not be surprised if there are whales keeping their coins at exchanges (!), especially in order to use them for trading, earning more, and, why not, manipulating the market a little when they can. Clearly, I talk here about whales who don't rely only on bitcoin for having all the goods they want in this life.

But.. this is how I imagine them. How do they behave in reality... we may never know.