The issue is that South Dakota allows you to declare residency without ever being there. You can get insurance, bank accounts and mail boxes without ever being in South Dakota. Expats with wealth use South Dakota to get access to American financial systems. A similar thing for Delaware which allows companies to incorporate for virtually nothing. So almost all companies of size are Delaware companies.
how can average people USE South Dakota for financial gain?....
The same reason SD is so popular with full time Rvers.