In a Q&A, it’s said that, before all the Horrors, Jon collected something. Something odd, not like coins or stamps.

My headcanon is that he collected some sort of blind box collectibles, I don’t what exactly, but one of the ones that has a mystery option.

And he kept collecting them because he had to know what the mystery one was. But he just kept getting the ones on the box, and he didn’t know what to do with them, so he keeps them.

He doesn’t want to give them away and let everyone know he buys them, he probably thinks it’s rather silly that he’s getting them at all, but he just has to know what the mystery one is.