That is a point Oracle. The difference is that none of those countries had complicated trading and regulatory agreements with the EU that were agreed without a thought to how to get out of them.
Your point about the future being bright might be true; or it might not be - anyone who tries to assure you of one or the other is clearly making it up. However, in the short to medium term, things are very likely to be trickier economically speaking than if we stayed in.