People who have a clue about the actual consequences, I'd say.

I can't speak for K~Ehleyr, but I have been following the Brexit matter closely since the debate started. The urban people, the educated, the young, overwhelmingly voted "Remain". So did some geographical/economical minorities (notably Scotland). The bulk of "Leave" voters were working class folk, afraid because they're losing their jobs to Polish plumbers. They have been lied to, their fears exploited cynically. Now these people see that the foreign plumber isn't going away anyway, but the City workers who used to be their customers at lunchtime or when their expensive shirts needed washing are going away if the government isn't able to negotiate merciful terms. And things look like the they won't be able to.

This is not about centralization/decentralization IMO. It's about an open market or a closed market. It's much harder to produce (or keep) wealth in the latter. Some of the uneducated are beginning to realize what happened above their heads, and they aren't going to be happy about that.