Of course the Big 5 don't trade together, that was just an analogy. I could equally have compared it to kids in the playground. You might feel morally superior if you don't join the gang but it's lonely and difficult on your own!
Btw, anyone who thinks Remainers are willing Brexit to be a catastrophe, just to be proved right, isn't being realistic. This isn't a game. We all live in the same economy and we all suffer when the pound falls, or prices rise, or public spending is cut...I think I can say, on behalf of all in the Remain camp, that we would be delighted to be proved wrong by a booming economy and cast-iron guarantees on the legislation we've come to take for granted, just as maternity/paternity rights. On a personal level, I'm hoping to visit my daughter in the US this year and I would be extremely happy to see the pound rise against the dollar, as the value of our spending money has just been halved!
It seems to me that there is a lot of wishful thinking going on, without much basis in fact. Even if our former trading partners in Europe are able to do business with us unilaterally, will they want to? Why would they want the hassle of dealing with UK red tape when they could much more easily trade with other countries within the same market? And won't they want the protection offered to them by EU legislation, particularly if it is a matter of investing their money? After all, we're not the only country in the world and, if they can trade with other EU countries more easily and with more security, why should they put themselves through the bother?