Well apparently we should leave so we can stop trading with the 500 million strong single market on our door step, and instead overnight negotiate replacement trade treaties with other countries and the EU itself (which in our case will definitely not take the usual years and years of talks for some important reason that Boris hasn't quite fully explained yet).
Armed with these treaties, we will then suddenly become a nimble economy pursuing more lucrative opportunities with China, the USA and erm, Russia.
Life in the UK will be amazing, especially once all those pesky large companies and banks move their HQs and operations quietly out of the UK to Frankfurt or Paris so they can still access the EU single market (and don't worry - both Germany and France have already met to work how to offer them incentives to reduce their operations in the UK if we leave the EU). And the tech start ups too, as they can't get the staff or investment from the EU as easily.
There will be some awkward things to deal with of course. Like the President of China telling us it was best that we stay in the EU as that's where China wants to build links, at the EU level. And the US telling us we'd be at the back of the queue for trade treaties with them. And even Michael Gove admits that not everyone will keep their jobs if we leave. And of course, there will be a recession for a bit, naturally. And "nimble" is usually business speak for "reducing employment rights for employees".
But hey ho! You can't make an omelette without breaking some eggs, right?
Remain.