Yes, Bitcoin is stupid but take that 100 bucks in your pocket and buy it and don't sell it ever.
I think when I first heard about Bitcoin it was like 10 or 12 cents a piece. When the price reached a dollar everybody was like "the top is in - the party is over, guys"
Stop procrastinating so much, now I don't think just telling that to someone would change anything, but there is something I would tell him that happen because of it, that I am almost 100% sure would change his mind, and if I could show him better yet