Do poor people remain poor because of mindset or because the system around them is broken? I think it is both, sometimes the way people think makes them stuck and not move forward or achieve anything. Other times it's the society that makes life harder for poor people to rise.
Now let's discuss the mindset first, when someone is born poor, the person might think that it's okay and normal to be poor. Now when someone thinks like this all the time, such person might not work hard or even dream big because they believe nothing will change for them.
And there are some people that will be born poor and will dream big and work hard to leave poverty behind. They will want to get what the rich have and will definitely work towards it. That's how mindset works, what you believe is what will work for you.
The system too sometimes doesn't help the poor because no matter how hard they work the system fails them. There are some places that don't have good schools, no jobs no Healthcare facilities and others. Someone might want to start a business but won't get support because the system favours the rich and ignores the poor.
Corruption in government also makes things worse because the money and facilities meant for the poor will be stolen and used for something else or for personal greed.
So in as much as mindset matters, system change is also very important. We should train ourselves to believe in ourselves and aim higher, while the government should create good schools, good health care and also support the poor.
We need not just strong minds but strong system if we want to break poverty. When people have not just the right mindset but also live in fair society, they can rise.
Hey 
Image is mine.