All expert analysis is consistent that Brexit has cost around 5% of GDP, give or take.
It's not. That's not how any political figure works and if you think that all the experts agree then you're only viewing the side of the experts that tell you what you want to hear. In reality, absolutely nobody knows or can agree on any figures because figures in economics and politics are essentially bullshit.
What I mean by "bullshit" isn't that they're wrong but that their usage is wrong.
Let's take the statement "Brexit has cost around 5% of GDP, give or take" as a quick example.
What measure of GDP? How does it change if you change the measurements?
When are you measuring it from? I think it's unfair for you to measure it from there and you should measure it from here instead which gives a different figure.
How are you attaching that causality? How much have other global events taken off? How do you know? What other economies are you using to factor in impact for a global event? I think that is a bad measurement because their economy is different to ours and changes in this global event impacted them more than it does us, or less, or maybe not at all.
Why use GDP at all as a measurement of the success or failure of Brexit? I think we should use this metric which gives a different answer.
Who even says having less GDP is a bad thing? There's time when economic growth for the sake of economic growth can destroy a country.
Why are you judging the success or failure at this time? I believe it's too early because this treaty was only signed on this date and this thing happened and we need to give it a running in period.
How are you accounting for non-numeric successes such as return to sovereignty and other things that were a major part of Brexit yet you don't bother to account for them in your success and failure metric.
Continue ad nauseam.
It's never a winning strategy to attempt to use figures in what is essentially a philosophical argument. You have to be much more specific in defining what you consider to be pass and fail, which nobody who was talking about Brexit ever actually did before it happened, so now there's not criteria for it to be judged upon.
The question of whether Brexit works or not can be answered the same as the question of whether you believed Brexit works or not. It's like Greek Gods. They're real because you believe they're real.