With bitcoin, anything is possible. Looking at the current value, I personally think that bitcoin has the potential of reaching that value or even more, but probably within a period of five years or more. Reaching $500k within three years is a bit too little time, I personally think that your speculations might happen within a period of five years or even more. We are all aware that the market is so vlolatile but since the beginning of this year, the value of bitcoin has been increasing significantly, and this further proved that it has the potential of reaching that value.