Clearly, 51% are sufficiently convinced it's bad to want to leave.
The remainder are not made up of people who think it's good. Many of them also think the EU is bad or deeply flawed in various ways, but that either leaving is too risky due to the EU's stated guarantee of severe retaliation, or that the EU is bad but the UK could stay and fix it.
In my own family we split down the middle. Two voted out, two to remain. The two remainers voted to stay only because they feared the economic consequences, and the promised recession that was supposed to follow any vote to leave (it didn't). Neither of them are especially keen on the EU, although they don't dislike it either. They didn't really think about it much before.
