I like to understand what difference it makes from an economic standpoint ?
Is it mostly to do with trade ?
There is a huge amount of money going between countries in EU. It is far more than trade. Even when UK does not use Euro, it still contributes to coffers and get subsidies in agriculture and tons of other craps. It is like severing ties between California and rest of USA. Additionally, 3 millions of Europeans lives in UK and 2 millions Brits are in Continent. Their existence is now in question. The amount of money between UK and EU floating between these two are in billions per day. Once these ties get severed or limited. It will affect agricultural policy, space program, IT, education, pensions, health benefits, and even residency issues.