Low tax rates, lax regulation, and a relatively efficient and impartial court system (our courts are definitely in the pocket of capitalism, but not so much in the pocket of individual capitalists) have led to a proliferations of companies there, many of whose existence in Zug consists solely of a mailbox.

This has also led to a proliferation of local talent which looks passable in a suit, can open mailboxes, is versed in law and/or accounting, and does not steal excessive amounts of money.

The business model is basically "stuff that is not provably illegal yet". During the Cold War, Switzerland got away with a lot, but in recent years, many formerly lucrative areas of business started drying up thanks to stricter money laundering laws etc. So for an ecosystem that has evolved to accommodate financial engineering right at the edge of legality, cryptocurrency seemed almost a custom made niche.

For one thing, it has the lowest tax rate in Switzerland