there was a lesson I lean from here. when you are preaching to someone about Bitcoin, you shouldn't talk too much, and you shouldn't stay long and you should also allow them make some research and ask questions about what we are preaching to them, to avoid loss at the end.
It is pretty true. We just need to share necessary information about Bitcoin. And we must tell all the facts of it, don't preach someone based on our own opinion. Show the positive and negative sides, too. So, when he/she realizes the advantage and disadvantage of it, he/she won't be so surprised.