Always remember that for you to make a profit, somebody else has to make a loss,
not necessarily. imagine someone buys bitcoin at $1000 and then sells it to you at $2000 and you sell it at $4000. you both doubled your investment and "won.
The best way for a trader to measure success is by comparing their return to simply holding one side or the other. In your case, the price rose from $1000 to $4000, so the first trader lost $2000 and the second trader made $2000, for a net of $0 -- it is a zero-sum game when you remove the returns from simply holding.