Many would have heard about bitcoin wrongly and this has much to do with the kind of people that introduce them to bitcoin, some might have been lied to that they will never take any risk in it and cannot loose their money, while some already made mouth that its a quickest means to how someone can make money within a short period, all these wrong information's are what we should discourage others from giving newbies, we should present bitcoin as it it to them and not to entice them, because we loose nor gain nothing from that, and every newbies should also take the task on themselves to make personal research in addition to what they had been told.
You are right that one should let a person they are teaching about Bitcoin know that it involves risks, however, I don't think a person can lose money after investing in Bitcoin if they are not getting into futures or other trading types and are just buying and storing and also are patient enough to keep holding through bad times, but then again, it's a matter of guidance, if you are talking about Bitcoin investments to someone, let them know each and everything so that they don't face problems, because if they face problems and incur losses, you are the one they are going to blame for their losses and then you won't be able to say anything because you didn't guide them well.