The EU ruined itself by existing. It tried to integrate divergent and variously developed economies under a system which imposed one-size fits all solutions, thus creating massive stress. As the years went by it's policies just created more and more stress an already fragile system.
Not taking the Euro was the smartest thing that the UK did when joining that organization, it'll make leaving that much more painless. I hope the break is clean and the UK can form powerful economic relationships with its former colonies and fellow 5-eyes nations.