This part is very interesting. I'm guessing you didn't bring up the word "sin"? Looks like he brought it up.

Maybe he has a guilty conscience.

He probably understands that what he's doing amounts to nothing more than gambling/speculation. But it's working for him and he's having some fun doing it, so it reminds me of people who are slightly guilty about their indulgence in mindless entertainments, but not guilty enough to stop.

For people on that edge, it's enough for me that they have a bit of a conscience about it. When trading gets boring, or he hits a rough streak, he'll think back to your words.