Because it's going to be years until we know of the outcome and therefore years before we know what, if any, part of it will be positive.
The negative impact of Brexit is already well-established. The positive outcomes are currently up in the air.
My pessimism is based on 4 simple facts:
1). Economic uncertainty is not a good thing.
2). Trade uncertainty is not a good thing.
3). A giant fall in the Pound is not a good thing.
4). The EU will not make life easy for us because they want to show other members why choosing to leave is not a good idea. Call it vindictive if you want, but that is what will happen. Let's all be honest here folks, there is one way the EU could ensure that no other member dare even thinks of leaving: if the UK ends up on its knees.
The Pound will pick up a little bit, but you just have to look at the overall environment to see why it's going to struggle. It will take years not only to negotiate our exit, but to also negotiate new trade deals with the world. Only the most daring traders and investors will come in during this time to gamble on everything turning out fine. The rest will either short against the Pound or simply steer clear.
One thing for certain is that this will continue until there is a formal agreement - signed, sealed and delivered - on exactly what the UK's post-EU relationship with Europe and the world is going to look like.
Any perceived positives at this stage are also fraught with doubt:
Make our own trade agreements - are they actually going to be any better than they are now, or even equally favourable at all?
Control our own laws - what will the Government now do with workers' rights and our human rights?
Control immigration - how much will it really go down? Will there be an unprecedented surge of migrants entering the UK in the next two years to settle before the door closes? A gradual growth in immigration whilst the economy expands along with it is fine. A giant surge all at the same time when the economy is in a recession is not.
The negatives are already visible for all to see. The positives, meanwhile, are still highly uncertain and come with the distinct possibility that they may turn out to be negatives in many respects as well.
The negative effects are well established after just 12 hours of the vote being made official? Are you trying to sound daft?
The positive outcomes are still in the air, after just 12 hours of the vote being made official, again, are you trying to sound daft?
Economic uncertainty is bad? Not for everyone.
Trade uncertainty is bad? Trade will continue, either cheaper or more expensive, probably a mixture of the two.
A giant fall in the pound is bad? Again, not for all.
The EU will want a quick divorce, but the treaties allow for a two year negotiation, and after a day or two to calm down they will find just like us they would prefer to remain good trade partners.
Our own trade deals better or worse? Give it time, same for workers rights, but why do you believe a GOV would reduce them when at the election the elecorate could then replace them if found to be unfair and wrong?
Will immigration go down? Once we regain full control of the borders, until then EU nationals will probably increase.
As for the citys two favorites, the pound is a self fulfilling prophecy, the banks are making billions today and will keep this going as long as they can, the stock market even after todays falls are higher than the day the EU referendum was announced.
Time for people to stop running the country down and start being a bit more positive IMO, do any of us business people run our businesses with such a negative attitude?
Do you control exchange rates, immigration, legislation etc as a business, or do you simply react and adapt? No person, business or country controls everything, change is always on the cards, and it can be good or bad, down to us as a country to decide which we prefer, because whatever we choose will almost certainly be the correct answer.