Well, I would imagine it's something like: If the promoters are booking in bands that are pulling in punters, the venue's going to make a lot of money on the bar. Plus on top of that, some of them charge a hire fee, and/or a deposit if x amount of £ isn't made on the bar on the night. So they're at least covering their costs and maybe getting a bit more on top. Running a venue is obviously a lot of work and trying to keep it busy all the time and booking bands/DJs etc is obviously even more work, so it's often to the benefit of the venue to take on more people to ease the burden, especially if they're people who can bring in something a little different and help boost the venue's image/reputation. The result - more stuff going on, more money coming in. "why do independent promoters exist given that it's such a financial risk?" Because they don't have venues of their own, and everyone needs a hobby. ;-) There's plenty money to be made as well as lost if you get a good deal, especially if you've got a club open afterwards in a prime spot in 'town'. I know someone who walked away with 2 grand in his pocket after a recent Barfly gig + club, and that was after paying all the bands the fees their agents wanted...