That was the rumor that European socialist leaders propagated amonst the impoverished classes they had created. The wanted to get rid of them because they had learned that their states could no longer support them.
America never had "streets of gold". There were no streets paved with bricks that could be pried loose for personal wealth. It was about the opportunity to pave your own street.
...just a thought I had while sitting on the deck enjoying an adult beverage.