Did the refugee situation and the terrorist attacks in Paris and Brussels set off Brexit in the first place?

As someone who doesn't live in Europe it appears to me that the refugee problem in Syria combined with the terrorist attacks in Paris and Brussels, Belgium were potent triggers for the Brexit. Now, however, this also might cause a chain reaction of European Countries also exiting the Euro as well.

So, economically this could be a disaster for many countries like it already has been for Greece. It's kind of hard to know which way this all is going to go now. I wouldn't want to be in the British Prime Minister's position right now, for example. Because whatever he does likely isn't going to be popular right now. But, if he doesn't keep England in the Euro it could be the complete end of the EU in a chain reaction of the next 10 years with countries leaving the EU.

However, the one thing for sure is the stock markets worldwide likely are going to tank for a while either way just from the concussion of all interfacing events. (unless they already have found some sort of bottom) but I don't think so.