>Theresa May was initially against building a submarine out of cheese, obviously. Because it’s a completely insane thing to do.
Leaving the EU is not a completely insane thing to do.
The UK (and many other countries) have legitimate grievances about some things the EU is foisting on them (immigration for example) and the EU is giving them the cold shoulder and fining them if they don't comply. Labelling people who are against that as "insane" isn't going to help anybody.