If I have a lot of EtH (otherwise then use word majority) I would actually sell them to get Bitcoin. The main reason would be that I trust Bitcoin more. For years I have witnessed how it always lead the market, how it is first to gain and gain more than ETH in % ratio. Secondary reason, if I really have a lot of ETH, then diversifying eggs into several baskets is always good. Third reason - I dont like ETH that much anymore. I dont like how its transaction fees went up from cents to dollars and never go back. Bitcoin also had moments with high transaction fees, but they usually return to normal.