When we are talking about trading of the asset - bitcoin, then the price depend on the buy/sell offers.
If all offers of buyers are low the sellers can either accept the loss and sell at the moment or hold with the risk that the asset may lose even more value.
Assets like bitcoin have derivatives markers as well - futures, options, swaps, which deal with the movement and predictions of the price of the asset.
If the price of bitcoin goes low then ‘losers’ pay the ‘winners’- the people who predicted (wrongly) high price transfer assets to pay the people who predicted (correctly) low price.