Just first make sure to figure out how to keep him from using leverage and getting liquidated, which would certainly happen.
Holding Bitcoin feels like gambling. But Bitcoiners know it's a sure bet.
Bitcoin doubles its hardness every 4 years. Eventually Bitcoin will be infinitely hard and no other asset will be able to compete with it.
Some people say Bitcoin is the money of the future. More precisely, Bitcoin is the only money of the future that's here today. All the others will come and go. Same difference, I guess.
I suggest teaching the gambler about Bitcoin's value proposition. You get to ride a fractional share of the whole to infinity. Yee-haw!