At this point I think he won't change his mind lol.
Here is an example how folks getting an ideal to keep their fish in small tank.
The small LFS store owner told customer they can keep it in 20 gallons tank, if we suggest it's not a right tank for the fish then the customer will reply "Why? the store keep them in 5 gallons tank and my tank is 20 gallons....4 times bigger than the LFS tank!" That's an answer I got from a dude I meet in a small LFS" According to a honest staff members working there, he came back buying the same fish species 4 time within 2 months! The dude still not learn that fish he's wanted to keep can't survive in his 20 gallons tank.