I love quiz machines. The one I've been playing on tonight is one of my favourites. I'd much rather pump pound coins into a quiz machine than some arcade game with fancy graphics, or a fruit machine. It's the way a quiz machine forces you to recall information you thought you'd forgotten, or didn't realise you ever actually knew. I love it even more when there are several of you, surrounding a machine in a pub, pooling your knowledge, offering your skills at a "specialist subject". "Come on Dave, you're good at sports!" "Right Nel, try this music one, we're couting on you!" etc.
I don't think I've ever walked away from a machine with more money than when I approached it, but somehow that doesn't seem to be the point.