I asked my friend if he was going to buy bitcoin when it was 800. He said it was too expensive and he would wait for a dip.
This guy just isn't committed to buying Bitcoin. He obviously doesn't see its future as we do and he's not willing to take the risk to get a piece of the possible upside.
You should rephrase the question. If the pric today is $3700, ask him if he would rather buy Butcoin at $4500 in the future or at $3700 today?