I'm panicking now, my bitcoin has been falling for several days, my current assets are decreasing every day, and I wonder if I want to reduce the amount of bitcoin in my hands to reduce my loss.
No loss occurs until you sell at a loss. I seriously don't understand why people constantly try to "reduce" losses when the price has gone down already. It just doesn't make sense - accept that you are too late with selling, and that holding is the only right option for now. If you have some funds left, try to buy the market on the way down, and via that way lower the average buying price of your entire stash. It's just a matter of logical thinking, but that doesn't seem to apply to most of the people here.
I have enough funds left to buy the market on its way down, and for that reason look happily forward to an even lower price. If you go all in and have no funds left, yeah, you are limiting yourself unnecessarily.