Passing the tests is one thing, passing the training is another. World wide only about 50% of all those who pass selection become controllers and Switzerland is no exception. At the end of the day you also need, really need to like aircraft and have been bitten by the aviation bug. ATC like piloting is a great job and one for life. But you need to like the job, not just the conditions some employers offer. If you are an EU citizen then try NATS as well, the work will be more varied than in Switzerland. Hope you're successful. I.