I'll stand asides with Lucius on this one. Even for adults, that's a difficult thing to convince, let alone when that person has a parent who needs conviction beforehand. I can imagine most of the parents hearing "bitcoin" and depicting this as the "bad darkweb money" or as a bubbled-stock.
But at least there's an 18+ age limit earmarked on these platforms.
In addition, parents use them, and so will their children. You're obviously raising good points, but just be that parent for a sec.