Usually they simply just don't have enough information or get the wrong information from unreliable sources. They don't understand something, but that doesn't make it a scam.
Although there's a lot of ways for them to learn and have known about crypto, but people chooses not to. So, this thing will really depend on them if they want to know it then Google is the key, if they don't then they won't find a way to get through it.
Anyway, as for my family and friends that still don't believe in Bitcoin up to this date, time will come they will tell to me that why I didn't push them to believe in me.