Musk has a lot of followers who wants to earn money. He made a big jump in price of doge coin and people have FOMO. And after news that Tesla wouldn't support bitcoin, they started to sell their coins.
    Also someone wanted to buy Tesla for 1 BTC. He or she bought BTC at $50000 and than they wanted to buy the car when the price will be more then 75,000 - $85 000.
    I think that bitcoin is like Apple shares now. Before new iPhone version the price rises, and after bad news it falls. This is normal market behavior.