Leaving the EU or ending free movement with EU countries leads to a significant increase in immigration from the third world, as Brexit showed.
The Swiss ruling class don’t have as much disdain for their populace. It will only end up that way if the Swiss people will it.
A lot of the UK’s problems were a result of the EU being vindictive as well. The EU won’t act vindictively because they aren’t in the EU.
It really doesn’t have to. Britain being incompetent is sort of its own chapter in governance.