I will first listen him why he hates Bitcoin after that I will clear the doubt of that person. But on the other hand some people mindset has different approach they don't want to understand. we can't convince such people leave those people you shouldn't worry about those peoples as we all know the potential of Bitcoin after some years when you will approach the same person again with growth of bitcoin value he must realize he was wrong about bitcoin that's the best thing you can do with such peoples.