I can’t work out if you’re deliberately being obtuse or you’re just blindly ignorant.
Firstly, the coronation will generate more money for the country than is spent, and much of it will directly be going into the pockets of small business owners: B&Bs and guesthouses, restaurants and cafes, retail and creators via memorabilia. Much of this will extend much further than the day, some even across decades such as books, film etc. It has been proven, time and time again, how much money comes in to the U.K. in the way of tourism because of the monarchy.
But an event such as a coronation also provides a cultural togetherness that is hard to recreate through other means except perhaps something like the Olympics or the World Cup. People, even many who on the surface seem to be anti-Royal, will be swept up in the pageantry of the event, feel they have gained through the extra Bank Holiday, and GASP, dare I say it, have a good time with their friends and family even if they aren’t directly celebrating. Not only will this generate an overall temporary positivity of mood, it will create more of a feeling of cohesiveness across the country — something that’s invaluable to cultivate during times of hardship, because it’s often that elevation that may make the difference between someone being able to carry on or not. And before you make a flippant statement that the RF can’t possibly make someone who is on the breadline happier, it’s not the individual people involved, it’s the overall togetherness and change of psychology that makes an impact. Culture matters way more than most people think, and it’s a cumulative effect that helps the most.
In addition, arguably a monarchy is a more robust, lower risk way of running a country. You have a buffer between the politics and the final decision-maker, however arbitrary that may feel, which means the politicians are accountable to SOMETHING beyond their own whims. Remove that and you’re asking for a system like the States.
Lastly, the budgets of a country do not cross over in the way many people like to think. You’re not dealing with an individual allocating a single salary into different purchases or bills. If we didn’t have the RF, that money isn’t going to magically solve the energy crisis or save the NHS. And even if, by some fluke, you could quantify getting rid of the RF in real terms of ‘money in pocket’ (which you can’t; an absence of something doesn’t give you extra money to spend, it simply prevents the spending of more, though I’ve already covered why it doesn’t work in this case), it would be a single sum allocated. One of the very obvious reasons this does nothing is because most of the issues any country faces (healthcare, pensions, social housing) are ongoing. You would need to get rid of a fictional RF every year to maintain any sort of remote impact. But since they actually generate money, you’re not just stating an opinion, you’re completely wrong.