It's so funny to think that people who don't have knowledge about bitcoin automatically thinks that bitcoin is a scam because of the issues regarding bitcoin scamming. So yeah.
Honestly, my first impression on bitcoin is almost the same as your friends, i'm also doubtful of the ability of bitcoin and i thought it was a scam. But in my long stay in the forum, I gradually learned about the true value of cryptocurrency and specially in bitcoin. So, we can't blame other people with less knowledge about it to doubt bitcoin, because it's really doubtful in the start.