People use Cayman because it’s a neutral and safe jurisdiction for global funds which plays nicely in the global financial system.

If you keep money in the US, and the beneficial owner of that money is in Singapore/UAE/China/etc, then profits are taxed twice.

If you operate in USA but earn money globally, then you’re subject to at least double, but sometimes a polynomial combination, of reporting and filling obligations from combinations of jurisdictions.

Cayman is clean, simple, above-board, and safe. It’s like a global money cache.