This is all political theater by the globalists. Switzerland is not in the EU and some of the most powerful companies in the world are headquartered in thriving Zurich, Geneva, Basel. The British could simply get the same deal with the EU that Switzerland has, if May wasn’t such a lightweight.
The British explicitly do not want the same deal that Switzerland has. The swiss EU deal is
1. Full freedom of eu citizens to live and work in Switzerland
2. Switzerland pays into the EU budget but does not have any decision making ability or influence
3. Switzerland needs to follow EU rules and regulations in order to continue trading.
The UK does not want this