It's important for young people to identify wehter invest or not in something that keeps growing. I mean, they are young and like to spend a lot of money, they also don't have too much for this and if they don't have a good management of their incomes it could turn into a nasty situation.
You are correct they don't have much money and generally like to spend what they have but that is why they need to start thinking about how they manage their money and consider saving.
This is regardless of whether they invest in bitcoin or not, saving for the future is just sound advice.