The 1970s were the height of social mobility. College was accessible. My grandfather was a poor immigrant who went to a public school in Ohio, and my father went to Harvard. That wasn't unusual. There was a feeling that anything was possible and you didn't have to be born into money to have a successful life. Now, people don't believe in the idea that anything is possible. We have more inequality than we've had ever before and a greater concentration of wealth in the hands of a few.

My photography is often a sociological look at American culture and it's been very well published in the UK.

These days, the media is defining what cultural capital is, and it's easily learned. If you have money, anything can be bought. We see this in China and Russia with what I call the "Bling Dynasty and New Oligarchy" in Generation Wealth. As people got rich and everybody started buying Louis Vuitton bags, it became clear that to distinguish yourself you had to have more than an expensive bag. People began to want the things that money is not supposed to be able to buy - history, tradition, education, and culture.

When I first moved from photography to filmmaking, I was worried about how big I had to become. I was one person, or maybe me and an assistant, and I had these small cameras, and maybe a flash.

What I'm documenting can be hard to distill, because it's all around us like the air we breathe. I often need to go to a place where I can capture extreme moments.

All my film ideas and subjects have come from photography.

You have these relationships with people that you care about, but I also try to stick to my job as filmmaker and be fair and truthful about what I saw and my experience of the people, hopefully informed by a deep understanding of them.