On a side-note: it's not easy the other way round either. Once you're a Swiss citizen, leaving the country can be a real pain. You need to prove that you're gone for good (or at last for 6 months) - otherwise they won't cash your "Säule 3a", they'll try to tax you wherever you may live and they'll even try to draft you for the military if your younger than 28.

Took my brother about a year to finally get rid of all the problems (AHV, military, taxes etc. etc.) and countless visits to the Swiss embassy when he decided to work in Hungary for a couple of years.

peter