The circuit finances and assembly hall finances are a scam indeed. There was a pot of about £800,000 in the maintenance fund a few years ago from an assembly hall in the UK (built by and with the donations of local brothers and sisters) which got spirited away to Watchtower London branch in the same way as a Kingdom Hall gets transferred to the branch office and any sums in the "remodelling/renovation/new build pot" goes too.
So in the UK they reckon that £10 per head is the "suggested donation rate" so an assembly of 1,000 people "costs" £10,000. This to sit in a hall built by the region's brothers and sisters, cleaned by them, looked after by them renovated by them - all for free.
Then three quarters of the way through the program the Circuit Assembly Overseer or his Asst. (Local free labour wannabe elders) gets up and says "at this point" the deficit is blah blah blah. The gullible put money into the box or via credit card at the credit card paying point(s) (Yup they got those too!) and then any surplus over a few hundred pounds is voted away "for the worldwide work" to branch HQ by the circuit elders at the "suggestion" of the Circuit Assembly Overseer.
So instead of building up a healthy balance they start each assembly with little money from the previous one and "need" to tell of a whopping deficit - and off they go again.
Now assuming they have about 35 weekends so 70 days use as assemblies per year at 10K this means they have an income of £700,000. Take out heat and light, cleaning materials and a caretaker couple who live on site and a car then I don't see how they don't make at least £600,000. Let's be generous and say "only" £500,000.
Then every 20 years do a refurbishment with free labour of course.
Nice little earner.