Less than three years from now? With a specific cryptocurrency (the most established but also the oldest)? Good luck with that. It sounds like ideology is getting in the way of good sense. On the other hand, he and his family aren’t currently trying to “Keep Up With the Joneses”, which will instill good habits whether or not this pays off.
If he can afford to lose it as a punt that’s fine, but if he’s risking everything and going long on it and holding that’s a different story.