For this example, even if you buy bitcoin at a higher price, and the current bitcoin price is lower than the buy-in, you sell it at all times for the current bitcoin price. Few buy bitcoins at a higher price than current coinmarketcap -
https://coinmarketcap.com/currencies/bitcoin/. These are the basics of trading and not just in the crypto area. In my opinion, if I bought a bitcoin for $ 17,000, i would certainly not sell it at a price of $ 6700. To conclude, the price of bitcoin is governed by supply and demand in the market.