Need help understanding selling..I have been reading on Bitcoin till my eyes bleed!..Please tell me If I am oversimplifying this...I buy a whole bitcoin on Coinbase..Hypothetically for 6k..I watch the graph and it goes to 7k all in the same day.I sell my Bitcoin @ 7k.. and just made a $1000.00?..Then can I turn around and buy another whole Bitcoin if it goes down again??