It's a hard one. I feel the UK were wrong to leave but Norway and Switzerland have a fantastic overall quality of life without and I'm not sure the benefits of membership unless you are financially poor country. Iceland is probably better off joining the Schengen but not EU.
Norway gets all the money it wanted from offshore gas, and Switzerland from being the bank of Europe when world wars happened (not mentioning gold nor laundering). When money is handed down to you like this by geography or history, the benefit of joining the eu and paying more for others is probably not given for the population.
If anything when your economy is based on European countries relying on your banking services, being part of EU makes it even easier for said countries to pour their money to your banks.