What will be the approximate bottom of the next bear market?

Hello fellow hodlers, I have a significant position of my portfolio in bitcoin at 70k and have been hodling all the way up and am anticipating to sell most of it at the next relative market top. I was wondering how low should the price action go because even if it drops significantly, if it dosent go under 70k then I don’t see a point in selling to get a better position. My time horizon is 40 years so I am debating even selling at all. Any feedback will help, thanks.