As I get more pessimistic about the world, I value more and more the institutions that have maintained stability in the world. Even though those same institutions (EU) have acted deplorably on many occasions. If we Leave, it could precipitate the break up of the EU.
On another thread, I saw some convincing arguments about why that might not be a bad idea - although I'm not yet convinced.
But my main conviction is about the United Kingdom. Departing the EU, I believe, will make it more likely for Scotland quite soon, and perhaps Northern Ireland later, to break up the United Kingdom.