Maybe they secretly wanted to be Batman.
Or maybe they've seen "Die Hard" too many times and wanted to know what Bruce Willis felt like when he jumped off the rooftop of an exploding building while riding a fire hose.
Or maybe it's just a nutty challenge and a chance to do some good in the Northwest suburbs.
"It was crazy! It was great! It was very exhilarating!"
That's how Nicole Abbatacola described rappelling down the side of the 21-floor Canon building at 425 N. Martingale Road in Schaumburg Saturday morning.
Abbatacola, of Arlington Heights, was the first of an estimated 50 people who went totally high-tech Tarzan on Saturday. It was her first time leaping down a building on a rope. Why?
"It was for a good cause," she said.
They all jumped at the chance to raise money for Habitat for Humanity of Northern Fox Valley.
"We were looking for something unique, something that we could do and, frankly, something that might attract a younger set of supporters," said Bill Klaves of Palatine, associate director of Northern Fox Valley's Habitat for Humanity, an organization dedicated to providing "simple, decent and affordable" housing.
Klaves' group teamed with Over the Edge, a Canadian fundraising team designed to pump funds into worthy nonprofits, by getting people to rappel down buildings.
"This has been on our to-do list for probably 10 years," Klaves said. "It was an idea whose time had come. We're thrilled to be here!"
One of the participants, Martin Porras of Elgin, has a special interest in Habitat: he's now working on the very house that he intends to buy for his two daughters and their mother.
"We are so thankful for the opportunity to put our own sweat into the building of our home," he said. "Years from now, I'll be able to tell my grandchildren, 'Hey, I built this house!' It's something special."
But how did the owner of the office building sign off on letting people jump off it and not give corporate attorneys liability nightmares?
"It was not easy," said Rick Needham, senior general manager of the Lincoln Property, a subsidiary of the building's real owner, New York Life Real Estate Investors. "It was a lot of work. Begging and pleading and making my case.
"After much, much persistence, I think he just gave in," Needham added. "To the credit of New York Life Real Estate Investors, they did it, and it was way outside their comfort zone, I'm sure."
Rappelling down 21 floors on Saturday was a little outside Abbatacola's comfort zone, too. "No, I did not look down," she admitted. "That would have freaked me out."
To support the fundraising effort, go to nfvrappel.org.