We tried being a republic once, we cut off a Divine Kings head. People didn't much like the alternative to not having a monarchy. God forbid we should go that way again and be like the States.
Plenty of countries in the Commonwealth who want to be there. The Australians rattle every so often and go all republican and voila! When they have a vote it is overwhelming to keep the status quo.
If you want some proper figures - the all in figures - the civil list is £7.1 million - thats been frozen for 21 years. - however all in including security for key Royals etc - ""The Royal Family spent £36.1m of taxpayers' money last year - a figure portrayed by royal aides as 56p for every person in the country. The Sovereign Grant, which is set at 15% of profits made by the Crown Estate, rose from £31m in 2012/13.""
So effectively that is offset by tax paid.
Revenue in to the Treasury is approximately 500 million
Of course if we do away with the Monarchy, what would you remove? Half of Europe with no actual monarchy is still as rich as Creosus and call themselves Prince of X or Grand Duke Y - they will still own their own money and painting and palaces and will keep on being rich because they can then work for personal gain.
So whether you like or agree with Royalty - they are a crowd puller - much like some people want to oggle any of the Kennedys.