The decreasing value of bitcoin nowadays is due to the Christmas season. More people withdraw their bitcoin investment or convert their bitcoins into flat because they need money for the Holiday. As we all know, Christmas is most expensive season because people buy gifts and food for their love ones. Also, during this season, only few people invest money. In connection with that, the bitcoin value decreases and being affected. This is the reason of your lost. But, do not lost hope because after this season, bitcoin value will increase again. And by then, your lost will recover and you will start earning bitcoin.