What pushes these daredevil photographers to the edge?

How high for a selfie?
How high for a selfie? 04:44

Last Updated Aug 15, 2017 2:57 AM EDT

"CBSN: On Assignment" airs Mondays at 10 p.m. ET/PT on CBS and on our streaming network, CBSN. To explore more on this topic click here.

I don't remember when I first saw a photo of someone dangling off a high-rise for the sake of, well, I'm sure I didn't know. I didn't know what to call them either. The journalistic basics, the "what" and "why," turned out to be tricky, much-debated aspects of our story on Victor Thomas. He's a 25-year-old photographer who likes to take pictures from the edge of tall buildings.

Victor Thomas, high above the skyline of Manhattan, in a photo he posted on Instagram. Instagram vic.invades

But is Vic an artist? A daredevil? A clear-eyed entrepreneur? Does he have more in common with mountain climbers or extreme athletes, X-Game All-Stars or art class rejects?

Vic is part of a tribe of thousands, spread across the world, one-upping each other on social media and flirting with riches and fame. Some call them "urban explorers," which struck me as ungainly and vague. Others call them "roofers" or "rooftoppers," which is more specific but also awkward and confusing. ("Roofers" calls to mind carpentry, not climbing.)

So I decided to let Vic define himself, and he did — holding forth for hours, on camera and off, at his grandmother's house in Brooklyn, a skate park nearby, and near the 400-foot tower he decided to climb.

Vic likes "urban explorer" because it suits everything he does from spelunking in old subway stations to scaling buildings. When we moved on to question of "why" Vic does what he does, though, he lost me.

Vic is a thoughtful, intelligent guy despite what you might think of his pastime. But to press him about his reasons is the conversational equivalent of walking off a main road into a mile-wide swamp.

At various points, Vic told me he climbs for money, for respect, for art. He told me does it to be different, or to be the same, or because it's fun. The truth is, there is no single, precise explanation.

Victor Thomas at the top of a Brooklyn high-rise construction site, from the drone footage of the climb. CBS News

The best writing I've found to describe Vic's pastime is from the Italian mountain climber Giusto Gervasutti. His notebooks were found in 1947 after he fell to his death in the French Alps. He was trying to explain why mountain climbers risk their lives for simple altitude, but his words stand as the best explanation of the itch for extreme living of all kinds.

That urge, he wrote, "may take the form of a need to live heroically, or to rebel against restraint and limitation: an escape from the restricting circle of daily life, a protest against being submerged in universal drabness, an affirmation of the freedom of the spirit in dangerous and splendid adventure." It may take the form of "the search for an intense aesthetic experience, for exquisite sensations, or for man's never satisfied desire for unknown country to explore, new paths to make. Best of all, it should be all these things together."

Urban exploration gives Vic all these things together.