Comment by WalterBright

What rich people immigrated here from Europe and founded dynasties in America?

How about one of the richest men in America? The son of a butcher:

https://en.wikipedia.org/wiki/John_Jacob_Astor#Early_life

How about the Kennedys? Irish immigrants:

https://en.wikipedia.org/wiki/P._J._Kennedy#Early_life

The Vanderbilts? From an indentured servant coming to America:

https://en.wikipedia.org/wiki/Cornelius_Vanderbilt#Ancestry