Not only friends, top notch finance proffesors here in my hometown also believe bitcoin is just bubble scheme. I try to describe blockchain to people and how its changing way of currencies, they just keep ignoring.
Time will explain that bitcoins are not as they think. as more and more bitcoin gets used by many people around them and then your friends will realize that they've missed a great opportunity to join bitcoin in the beginning. You do not have to be busy and have trouble telling them. time that will make them familiar with bitcoin because I'm sure bitcoin will be very famous in the future