I think that the most reasonable explanation for why the bitcoin price is going down is due to the fact that the major miners have stopped mining bitcoin and this lead to the miner fees going up and the transaction time increasing, along side these factors ethereum, bitcoin cash and some other altcoins were having an increase, and this lead to some people switching thier bitcoin to these ones to make profit from it, there is no telling what will be the stop point for bitcoin but the others are going down and as soon as the fees strat getting back to normal, i ma sure the price will start going up again.