Earlier quoted context omitted.
Nigel Farage made it clear that he wouldn't accept 52-48 as being decisive: "In a 52-48 referendum this would be unfinished business by a long way. If the Remain campaign win two-thirds to one-third that ends it." https://www.bbc.co.uk/news/uk-politics-eu-referendum-3630668...
The difference is that the referendum was stacked against leave in every conceivable way. For example, the remain campaign had £6m more to work with. On top of this the government spent £9m on pro remain leaflets and social media advertising. Add onto this the fact that the government wheeled out every 'expert' it could find to constantly cry about how bad brexit would be - most of them were lying (Mark Carney, Georg…
But on your WW2 point, I did think about it for a minute.
Britain fought WW2 for 6 years, 1939 – 1945. Brexit has no known endpoint. Imagine that even 10% of the trade impacts we've seen since the end of the transition period on 1 January persist. Then you can quite easily calculate how many years it will take to damage the economy more than WW2. Off the top of my head, I don't know if that's 6 years, or 60 years, or 600 years. But there's certainly some finite number that will do it.