None of my friends keep fish, although I have tried on a couple of them. They really like my tank but I think it looks too overwhelming for them. Unless you're passionate about fish, you're not going to do all the work required with a monster tank. I couldn't even talk them into a 'small' 125 gallon.
I still haven't seen a sump in person except for mine. I read up and looked at lots of pictures for a long time before putting mine together.
And no, I've never even run into another fishkeeper at a party or anything... If I did, I imagine the scenario would be a lot like you describe.