bitcoin slowly went down this year, from almost 20k USD last December and went down at a significant price
what might be the reason why bitcoin's price is going down?
what are the major things that can greatly influence bitcoin?
answers would be fully appreciated

Bitcoin's astronomical rise in 2017 paved way for a lot of new stuffs in cryptocurrency world, such things as Bitcoin Futures -which inadvertently has contributed immensely to the below-9k price of BTC this year and even more recently, the whole FUD and heightened expectations from G20 meeting scheduled in July would be a huge milestone.