Bitcoin keep on falling down and no sign of raising. How long can we keep holding?
Till you can get profit, you will not loss your money if you don't sell your coin in lower price. A few years ago bitcoin price is only about $200 but in line of bitcoin adoption the price is now increase, just wait.
It is good to wait and make sure you check the market cap of coin you have if the price goes up or down. Wait as long as possible, there is no exact time on how long you wait to sell. Sell if price is high to earn more profit, avoid selling low as your profit may be loss or less profit. At this time bitcoin price is at 8k right now and it may increase later on. As long as the price is down it is better to hold and be patience. Sell your coin if you really need money for emergencies or to provide something important.