@Ghost One of my saddest realisations I never seem to see coming ahead of time is when people I consider 'good friends' turn out to be 'good specific activity buddies' instead when I socialize with them out of context.
Once the realization sinks in that absent of the subject matter we usually talk about there really isn't that much we can talk about it's just downhill from there. And it's weird because in many cases I was having a blast with such folks, we're having fun... but once we take a step back and away from that comfortable bubble of familiar material it gets kinda awkward.
Or, worse, as you mention... the conversation just circles right back to the usual stuff. In your case it's LARP but I've seen it go to WoW or basketball in my circles, and it'd be nice to have more friendships transcending hobbies.
... The money-borrowing parts though were a big no-no.