I think its insane. Brexit was voted for by the British equivalent of our Trump voters, basically. The Brexit movement played on the same fears that Trump is playing upon: Immigration, jobs, white pride, nationalism, isolationism, etc. The economic implications, both for Britain, the EU, and the USA are huge.
There's also going to be a carry on effect, starting with Scotland, who has already said they will vote on leaving the UK and staying in the EU. Northern Ireland and the Republic of Ireland are now talking reunification and leaving the UK. That leaves Britain and Wales, and Wales is by no means a strong economic partner.
Here in the US, so far. The right wing conservatives are cheering Brexit because it follows along with their beliefs. Texas, which has been mumbling about secession for years, is becoming more and more organized in that direction, even though our constitution doesn't allow it.
Texas is cheering Brexit (I'm generalizing. There are liberal Democrats in Texas) . Personally, I'd as soon they leave. They take about twice from the government as what they contribute, and are a constant source of discord.
Like Brexit, Texas hasn't though of what losing their military bases, military contractors, federal prisons, etc, would do to their economy, not to mention the services they now get without charge as a member of the republic.
It'll be a nasty wakeup for them, just as it will for the Brits who voted Leave, when they realize how much more daily life is going to cost them without the support and backing of the EU.