1. Brexit's only REAL effect will lead to lack of influence on Europe and a loss of standing and prestige for Britain in the world - as the US and China have made clear.
2. Brexit will lead to the break up of Britain as Scotland will want to join Europe.
3. The cost of Britain's net contribution to the EU is about 1% of total expenditure - i.e. negligible.
4. Britain's economy is not very strong being unbalanced towards financial services and weak in manufacturing. This imbalance will grow if we left the Euro and lost links to large Euro projects e.g. Airbus. It also makes no sense for Japanese and other foreign car firms to stay in the UK.
5. It doesn't seem as if EU immigration will stop. Both Switzerland and Norway have larger per capita EU immigration than Britain and they are outside the EU.
6. We'll still have to follow Euro rules in exchange for trade rights as Switzerland and Norway have had to do.