In the case of my grandparents, they left behind MORE than poverty. They left oppression and hopelessness behind as well.
In America, their work secured their place for them and there were NO impediments to them, so long as they persevered. Of course, there was hardship and sacrifice, but who ever gained anything worth having without hardship and sacrifice? Also, they assimilated with eagerness, knowing that their children would have the best chance of success that way! Whining, pouting and grumbling were unthinkable! Laziness, crime and surly conduct were anathema!
The Ideal. notice the demon clouds chasing the people.
The reality. Notice the labels on each person.